SignalsIT#signalSchemaChanges test fails on Oracle 21 [DBZ-4722]

Migrated from [DBZ-4722](https://issues.redhat.com/browse/DBZ-4722)

This test was determined to fail on Oracle 21. It has been marked as incompatible and skipped for now and should likely be fixed when adderssing schema changes during Incremental Snapshots?

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io.debezium.connector.oracle.SignalsIT.signalSchemaChange Time elapsed: 363.595 s <<< FAILURE!
java.lang.AssertionError:
expected size:<8> but was:<2> for <[SourceRecord{sourcePartition={server=server1}, sourceOffset={snapshot=true, scn=4345927, snapshot_completed=false}} ConnectRecord{topic='server1', kafkaPartition=0, key=Struct{databaseName=ORCLPDB1}, keySchema=Schema{io.debezium.connector.oracle.SchemaChangeKey:STRUCT}, value=Struct{source=Struct{version=1.9.0-SNAPSHOT,connector=oracle,name=server1,ts_ms=1643918056103,snapshot=true,db=ORCLPDB1,schema=DEBEZIUM,table=CUSTOMER,scn=4345927},databaseName=ORCLPDB1,schemaName=DEBEZIUM,ddl=
CREATE TABLE "DEBEZIUM"."CUSTOMER"
( "ID" NUMBER(9,0) NOT NULL ENABLE,
"NAME" VARCHAR2(1000),
"SCORE" NUMBER(6,2),
"REGISTERED" TIMESTAMP (6),
CONSTRAINT "MYPK" PRIMARY KEY ("ID")
USING INDEX ENABLE,
SUPPLEMENTAL LOG DATA (ALL) COLUMNS
) ;,tableChanges=[Struct{type=CREATE,id="ORCLPDB1"."DEBEZIUM"."CUSTOMER",table=Struct{primaryKeyColumnNames=[ID],columns=[Struct{name=ID,jdbcType=2,typeName=NUMBER,typeExpression=NUMBER,length=9,scale=0,position=1,optional=false,autoIncremented=false,generated=false}, Struct{name=NAME,jdbcType=12,typeName=VARCHAR2,typeExpression=VARCHAR2,length=1000,position=2,optional=true,autoIncremented=false,generated=false}, Struct{name=SCORE,jdbcType=2,typeName=NUMBER,typeExpression=NUMBER,length=6,scale=2,position=3,optional=true,autoIncremented=false,generated=false}, Struct{name=REGISTERED,jdbcType=93,typeName=TIMESTAMP(6),typeExpression=TIMESTAMP(6),length=6,position=4,optional=true,autoIncremented=false,generated=false}]}}]}, valueSchema=Schema{io.debezium.connector.oracle.SchemaChangeValue:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}, SourceRecord{sourcePartition={server=server1}, sourceOffset={snapshot=true, scn=4345927, snapshot_completed=false}} ConnectRecord{topic='server1', kafkaPartition=0, key=Struct{databaseName=ORCLPDB1}, keySchema=Schema{io.debezium.connector.oracle.SchemaChangeKey:STRUCT}, value=Struct{source=Struct{version=1.9.0-SNAPSHOT,connector=oracle,name=server1,ts_ms=1643918056306,snapshot=last,db=ORCLPDB1,schema=DEBEZIUM,table=DEBEZIUM_SIGNAL,scn=4345927},databaseName=ORCLPDB1,schemaName=DEBEZIUM,ddl=
CREATE TABLE "DEBEZIUM"."DEBEZIUM_SIGNAL"
( "ID" VARCHAR2(64),
"TYPE" VARCHAR2(64),
"DATA" VARCHAR2(2048),
SUPPLEMENTAL LOG DATA (ALL) COLUMNS
) ;,tableChanges=[Struct{type=CREATE,id="ORCLPDB1"."DEBEZIUM"."DEBEZIUM_SIGNAL",table=Struct{primaryKeyColumnNames=[],columns=[Struct{name=ID,jdbcType=12,typeName=VARCHAR2,typeExpression=VARCHAR2,length=64,position=1,optional=true,autoIncremented=false,generated=false}, Struct{name=TYPE,jdbcType=12,typeName=VARCHAR2,typeExpression=VARCHAR2,length=64,position=2,optional=true,autoIncremented=false,generated=false}, Struct{name=DATA,jdbcType=12,typeName=VARCHAR2,typeExpression=VARCHAR2,length=2048,position=3,optional=true,autoIncremented=false,generated=false}]}}]}, valueSchema=Schema{io.debezium.connector.oracle.SchemaChangeValue:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}]>
at io.debezium.connector.oracle.SignalsIT.signalSchemaChange(SignalsIT.java:116)
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Start with the failing io.debezium.connector.oracle.SignalsIT.signalSchemaChange test at SignalsIT.java:116 and reproduce it against Oracle 21. Review why the test is marked incompatible and skipped, especially around schema changes during incremental snapshots. Done means the test produces the expected schema-change records on Oracle 21 without the failure.

Written by the indexing model from the issue text.