Walk over IntelliJ's "unused declaration" regarding variable declarations

Similar story to #7780. Until we haven't solved #6860, there are a lot of (less important) warnings on unused methods than on unused variables. All reports on variables are bugs.

4 in production (#7742 was fifth):
```

file://$PROJECT_DIR$/server/src/main/java/org/apache/druid/client/CachingQueryRunner.java
136
druid-server
org.apache.druid.client

Unused declaration
Variable <code>cacheFutures</code> is never used

file://$PROJECT_DIR$/server/src/main/java/org/apache/druid/initialization/Log4jShutterDownerModule.java
54
druid-server
org.apache.druid.initialization

Unused declaration
Variable <code>logManagerClazz</code> is never used

file://$PROJECT_DIR$/server/src/main/java/org/apache/druid/initialization/Log4jShutterDownerModule.java
56
druid-server
org.apache.druid.initialization

Unused declaration
Variable <code>callbackRegistryClazz</code> is never used

file://$PROJECT_DIR$/sql/src/main/java/org/apache/druid/sql/calcite/table/RowSignature.java
60
druid-sql
org.apache.druid.sql.calcite.table

Unused declaration
Variable <code>i</code> is never used

```

63 more in test code:
```

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/DruidCoordinatorBalancerProfiler.java
259
druid-server
org.apache.druid.server.coordinator

Unused declaration
Variable <code>balanceParams</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/DruidCoordinatorBalancerProfiler.java
185
druid-server
org.apache.druid.server.coordinator

Unused declaration
Variable <code>balanceParams</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/DruidCoordinatorBalancerProfiler.java
186
druid-server
org.apache.druid.server.coordinator

Unused declaration
Variable <code>assignParams</code> is never used

file://$PROJECT_DIR$/extensions-contrib/influx-extensions/src/test/java/org/apache/druid/data/input/influx/InfluxParserTest.java
195
druid-influx-extensions
org.apache.druid.data.input.influx

Unused declaration
Variable <code>res</code> is never used

file://$PROJECT_DIR$/integration-tests/src/main/java/org/apache/druid/testing/clients/CoordinatorResourceTestClient.java
244
druid-integration-tests
org.apache.druid.testing.clients

Unused declaration
Variable <code>results</code> is never used

file://$PROJECT_DIR$/extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/KafkaIndexTaskTest.java
1645
druid-kafka-indexing-service
org.apache.druid.indexing.kafka

Unused declaration
Variable <code>desc3</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RealtimeIndexTaskTest.java
969
druid-indexing-service
org.apache.druid.indexing.common.task

Unused declaration
Variable <code>segmentLoaderConfig</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java
986
druid-indexing-service
org.apache.druid.indexing.common.task

Unused declaration
Variable <code>ingestionSpecs</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java
950
druid-indexing-service
org.apache.druid.indexing.common.task

Unused declaration
Variable <code>task</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java
1125
druid-indexing-service
org.apache.druid.indexing.common.task

Unused declaration
Variable <code>task</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java
1590
druid-indexing-service
org.apache.druid.indexing.common.task

Unused declaration
Variable <code>segmentLoaderConfig</code> is never used

file://$PROJECT_DIR$/extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/supervisor/KafkaSupervisorTest.java
340
druid-kafka-indexing-service
org.apache.druid.indexing.kafka.supervisor

Unused declaration
Variable <code>taskConfig</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskManagerTest.java
96
druid-indexing-service
org.apache.druid.indexing.worker

Unused declaration
Variable <code>loaderConfig</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactoryTest.java
462
druid-indexing-service
org.apache.druid.indexing.firehose

Unused declaration
Variable <code>numSegments</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/overlord/TaskLifecycleTest.java
545
druid-indexing-service
org.apache.druid.indexing.overlord

Unused declaration
Variable <code>segmentLoaderConfig</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/overlord/http/OverlordResourceTest.java
740
druid-indexing-service
org.apache.druid.indexing.overlord.http

Unused declaration
Variable <code>ds</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/overlord/http/OverlordResourceTest.java
793
druid-indexing-service
org.apache.druid.indexing.overlord.http

Unused declaration
Variable <code>tasksIds</code> is never used

file://$PROJECT_DIR$/indexing-service/src/test/java/org/apache/druid/indexing/overlord/http/OverlordResourceTest.java
675
druid-indexing-service
org.apache.druid.indexing.overlord.http

Unused declaration
Variable <code>ds</code> is never used

file://$PROJECT_DIR$/extensions-core/lookups-cached-global/src/test/java/org/apache/druid/query/lookup/namespace/UriExtractionNamespaceTest.java
154
druid-lookups-cached-global
org.apache.druid.query.lookup.namespace

Unused declaration
Variable <code>map</code> is never used

file://$PROJECT_DIR$/extensions-core/lookups-cached-global/src/test/java/org/apache/druid/query/lookup/namespace/UriExtractionNamespaceTest.java
168
druid-lookups-cached-global
org.apache.druid.query.lookup.namespace

Unused declaration
Variable <code>map</code> is never used

file://$PROJECT_DIR$/extensions-core/lookups-cached-global/src/test/java/org/apache/druid/query/lookup/namespace/UriExtractionNamespaceTest.java
118
druid-lookups-cached-global
org.apache.druid.query.lookup.namespace

Unused declaration
Variable <code>map</code> is never used

file://$PROJECT_DIR$/processing/src/test/java/org/apache/druid/query/scan/ScanQueryTest.java
270
druid-processing
org.apache.druid.query.scan

Unused declaration
Variable <code>res</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/query/lookup/LookupReferencesManagerTest.java
603
druid-server
org.apache.druid.query.lookup

Unused declaration
Variable <code>responseHolder</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/query/lookup/LookupReferencesManagerTest.java
80
druid-server
org.apache.druid.query.lookup

Unused declaration
Variable <code>temporaryPath</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/client/cache/MemcacheClientPoolTest.java
65
druid-server
org.apache.druid.client.cache

Unused declaration
Variable <code>garbage</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/client/cache/CacheConfigTest.java
129
druid-server
org.apache.druid.client.cache

Unused declaration
Variable <code>config</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/client/cache/CacheConfigTest.java
157
druid-server
org.apache.druid.client.cache

Unused declaration
Variable <code>config</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/client/cache/CacheConfigTest.java
147
druid-server
org.apache.druid.client.cache

Unused declaration
Variable <code>config</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/client/cache/CacheConfigTest.java
138
druid-server
org.apache.druid.client.cache

Unused declaration
Variable <code>config</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/client/client/BatchServerInventoryViewTest.java
497
druid-server
org.apache.druid.client.client

Unused declaration
Variable <code>announcers</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/http/LookupCoordinatorResourceTest.java
799
druid-server
org.apache.druid.server.http

Unused declaration
Variable <code>retVal</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/http/LookupCoordinatorResourceTest.java
725
druid-server
org.apache.druid.server.http

Unused declaration
Variable <code>ip</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/DataSourceCompactionConfigTest.java
176
druid-server
org.apache.druid.server.coordinator

Unused declaration
Variable <code>config</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/DataSourceCompactionConfigTest.java
155
druid-server
org.apache.druid.server.coordinator

Unused declaration
Variable <code>config</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/rules/ForeverLoadRuleTest.java
75
druid-server
org.apache.druid.server.coordinator.rules

Unused declaration
Variable <code>reread</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordinator/rules/ForeverLoadRuleTest.java
89
druid-server
org.apache.druid.server.coordinator.rules

Unused declaration
Variable <code>reread</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordination/ChangeRequestHistoryTest.java
77
druid-server
org.apache.druid.server.coordination

Unused declaration
Variable <code>four</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordination/ChangeRequestHistoryTest.java
110
druid-server
org.apache.druid.server.coordination

Unused declaration
Variable <code>three</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/server/coordination/ChangeRequestHistoryTest.java
113
druid-server
org.apache.druid.server.coordination

Unused declaration
Variable <code>four</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/segment/indexing/DataSchemaTest.java
314
druid-server
org.apache.druid.segment.indexing

Unused declaration
Variable <code>schema</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/segment/indexing/granularity/ArbitraryGranularityTest.java
134
druid-server
org.apache.druid.segment.indexing.granularity

Unused declaration
Variable <code>spec</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/segment/indexing/granularity/ArbitraryGranularityTest.java
168
druid-server
org.apache.druid.segment.indexing.granularity

Unused declaration
Variable <code>spec</code> is never used

file://$PROJECT_DIR$/server/src/test/java/org/apache/druid/segment/realtime/firehose/EventReceiverFirehoseTest.java
232
druid-server
org.apache.druid.segment.realtime.firehose

Unused declaration
Variable <code>firehose2</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
648
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement1</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
649
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement2</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
650
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement3</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
651
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement4</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
655
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement5</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
762
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>connection4</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
736
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement1</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
739
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement2</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
742
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>statement3</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/avatica/DruidAvaticaHandlerTest.java
747
druid-sql
org.apache.druid.sql.avatica

Unused declaration
Variable <code>connection4</code> is never used

file://$PROJECT_DIR$/sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java
5225
druid-sql
org.apache.druid.sql.calcite

Unused declaration
Variable <code>nullValue</code> is never used

file://$PROJECT_DIR$/extensions-contrib/materialized-view-maintenance/src/test/java/org/apache/druid/indexing/materializedview/MaterializedViewSupervisorSpecTest.java
253
materialized-view-maintenance
org.apache.druid.indexing.materializedview

Unused declaration
Variable <code>materializedViewSupervisorSpec</code> is never used

file://$PROJECT_DIR$/extensions-contrib/materialized-view-maintenance/src/test/java/org/apache/druid/indexing/materializedview/MaterializedViewSupervisorSpecTest.java
208
materialized-view-maintenance
org.apache.druid.indexing.materializedview

Unused declaration
Variable <code>materializedViewSupervisorSpec</code> is never used

file://$PROJECT_DIR$/extensions-contrib/materialized-view-maintenance/src/test/java/org/apache/druid/indexing/materializedview/DerivativeDataSourceMetadataTest.java
46
materialized-view-maintenance
org.apache.druid.indexing.materializedview

Unused declaration
Variable <code>metadata</code> is never used

file://$PROJECT_DIR$/extensions-contrib/materialized-view-maintenance/src/test/java/org/apache/druid/indexing/materializedview/DerivativeDataSourceMetadataTest.java
59
materialized-view-maintenance
org.apache.druid.indexing.materializedview

Unused declaration
Variable <code>metadata</code> is never used

file://$PROJECT_DIR$/extensions-contrib/moving-average-query/src/test/java/org/apache/druid/query/movingaverage/MovingAverageIterableTest.java
460
druid-moving-average-query
org.apache.druid.query.movingaverage

Unused declaration
Variable <code>event4</code> is never used

file://$PROJECT_DIR$/extensions-contrib/influxdb-emitter/src/test/java/org/apache/druid/emitter/influxdb/InfluxdbEmitterConfigTest.java
95
druid-influxdb-emitter
org.apache.druid.emitter.influxdb

Unused declaration
Variable <code>influxdbEmitterConfigWithNullPort</code> is never used

file://$PROJECT_DIR$/extensions-contrib/influxdb-emitter/src/test/java/org/apache/druid/emitter/influxdb/InfluxdbEmitterConfigTest.java
147
druid-influxdb-emitter
org.apache.druid.emitter.influxdb

Unused declaration
Variable <code>influxdbEmitterConfigWithNullHostname</code> is never used

file://$PROJECT_DIR$/extensions-contrib/influxdb-emitter/src/test/java/org/apache/druid/emitter/influxdb/InfluxdbEmitterConfigTest.java
79
druid-influxdb-emitter
org.apache.druid.emitter.influxdb

Unused declaration
Variable <code>influxdbEmitterConfigWithNullHostname</code> is never used

file://$PROJECT_DIR$/extensions-contrib/influxdb-emitter/src/test/java/org/apache/druid/emitter/influxdb/InfluxdbEmitterConfigTest.java
163
druid-influxdb-emitter
org.apache.druid.emitter.influxdb

Unused declaration
Variable <code>influxdbEmitterConfigWithNullHostname</code> is never used

```

Start with the listed Java files, including server/src/main/java/org/apache/druid/client/CachingQueryRunner.java, server/src/main/java/org/apache/druid/initialization/Log4jShutterDownerModule.java, and sql/src/main/java/org/apache/druid/sql/calcite/table/RowSignature.java. Review each reported variable in its enclosing method, then run the relevant module tests or build checks; done means the listed unused-variable warnings are removed without changing behavior.

Written by the indexing model from the issue text.