Constant CI test failures for Db2 connector [DBZ-7163]

Migrated from [DBZ-7163](https://issues.redhat.com/browse/DBZ-7163)

{code}
[INFO] Results:
[INFO]
Error: Failures:
Error: Db2ConnectorIT.restartInTheMiddleOfTx:698->restartInTheMiddleOfTx:603
Expected size:<30> but was:<0> in:
<[]>
Error: Db2ConnectorIT.restartInTheMiddleOfTxAfterCompletedTx:692->restartInTheMiddleOfTx:585->assertRecord:897->lambda$assertRecord$4:897 [Values don't match for ID] expected:<[-2]> but was:<[1001]>
Error: Db2ConnectorIT.restartInTheMiddleOfTxAfterSnapshot:686->restartInTheMiddleOfTx:603
Expected size:<30> but was:<0> in:
<[]>
Error: Db2OnlineDefaultValueIT>AbstractDb2DefaultValueIT.shouldHandleDateTimeDefaultTypes:200->AbstractDb2DefaultValueIT.shouldHandleDefaultValuesCommon:214->AbstractDb2DefaultValueIT.testDefaultValuesAlterTableAdd:490->AbstractDb2DefaultValueIT.assertSchemaFieldWithDefaultCurrentDate:541->AbstractDb2DefaultValueIT.assertSchemaFieldValueWithDefault:537->AbstractDb2DefaultValueIT.lambda$assertSchemaFieldWithDefaultCurrentDate$2:549 [Unexpected field value: AVAL_DATE_SYSDATE_NONNULL]
Expecting:
<-719162>
to be greater than or equal to:
<1>
Error: IncrementalSnapshotIT>AbstractIncrementalSnapshotTest.snapshotWithNewAdditionalConditionsField:754->AbstractConnectorTest.assertNoRecordsToConsume:982 expected:<[tru]e> but was:<[fals]e>
Error: TransactionMetadataIT.transactionMetadata:101
Expected size:<5> but was:<3> in:
<[SourceRecord{sourcePartition={server=testdb}, sourceOffset={transaction_id=00000000:00001834:0000000000048b83, event_serial_no=1, commit_lsn=00000000:00001834:0000000000048b83, change_lsn=00000000:00000000:00000000056ae8c8, transaction_data_collection_order_DB2INST1.TABLEA=1}} ConnectRecord{topic='testdb.DB2INST1.TABLEA', kafkaPartition=null, key=Struct{ID=10}, keySchema=Schema{testdb.DB2INST1.TABLEA.Key:STRUCT}, value=Struct{after=Struct{ID=10,COLA=a},source=Struct{version=2.5.0-SNAPSHOT,connector=db2,name=testdb,ts_ms=1700326695853,db=testdb,schema=DB2INST1,table=TABLEA,change_lsn=00000000:00000000:00000000056ae8c8,commit_lsn=00000000:00001834:0000000000048b83},op=c,ts_ms=1700326695853,transaction=Struct{id=00000000:00001834:0000000000048b83,total_order=1,data_collection_order=1}}, valueSchema=Schema{testdb.DB2INST1.TABLEA.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)},
SourceRecord{sourcePartition={server=testdb}, sourceOffset={transaction_id=00000000:00001836:0000000000048b89, event_serial_no=1, commit_lsn=00000000:00001836:0000000000048b89, change_lsn=00000000:00000000:00000000056aea90, transaction_data_collection_order_DB2INST1.TABLEA=1}} ConnectRecord{topic='testdb.DB2INST1.TABLEA', kafkaPartition=null, key=Struct{ID=11}, keySchema=Schema{testdb.DB2INST1.TABLEA.Key:STRUCT}, value=Struct{after=Struct{ID=11,COLA=a},source=Struct{version=2.5.0-SNAPSHOT,connector=db2,name=testdb,ts_ms=1700326695872,db=testdb,schema=DB2INST1,table=TABLEA,change_lsn=00000000:00000000:00000000056aea90,commit_lsn=00000000:00001836:0000000000048b89},op=c,ts_ms=1700326695872,transaction=Struct{id=00000000:00001836:0000000000048b89,total_order=1,data_collection_order=1}}, valueSchema=Schema{testdb.DB2INST1.TABLEA.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)},
SourceRecord{sourcePartition={server=testdb}, sourceOffset={transaction_id=00000000:00001838:0000000000048b8f, event_serial_no=1, commit_lsn=00000000:00001838:0000000000048b8f, change_lsn=00000000:00000000:00000000056aec58, transaction_data_collection_order_DB2INST1.TABLEA=1}} ConnectRecord{topic='testdb.DB2INST1.TABLEA', kafkaPartition=null, key=Struct{ID=12}, keySchema=Schema{testdb.DB2INST1.TABLEA.Key:STRUCT}, value=Struct{after=Struct{ID=12,COLA=a},source=Struct{version=2.5.0-SNAPSHOT,connector=db2,name=testdb,ts_ms=1700326695874,db=testdb,schema=DB2INST1,table=TABLEA,change_lsn=00000000:00000000:00000000056aec58,commit_lsn=00000000:00001838:0000000000048b8f},op=c,ts_ms=1700326695874,transaction=Struct{id=00000000:00001838:0000000000048b8f,total_order=1,data_collection_order=1}}, valueSchema=Schema{testdb.DB2INST1.TABLEA.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}]>
Error: Errors:
Error: Db2ConnectorIT.updatePrimaryKey:228->assertRecord:897->lambda$assertRecord$4:897 » NullPointer Cannot invoke "org.apache.kafka.connect.data.Struct.schema()" because "content" is null
{code}

The restartInTheMiddleOfTx error was previously reported as DBZ-6849

Start by reproducing the failures in Db2ConnectorIT, Db2OnlineDefaultValueIT, IncrementalSnapshotIT, and TransactionMetadataIT, then inspect the named failing methods and assertions. Determine whether the failures share a Db2 connector cause or need separate fixes; done means the listed CI tests pass consistently, including the restart, default-value, snapshot, transaction metadata, and primary-key cases.

Written by the indexing model from the issue text.