[Test] Wait for asynchronous table deletion in session IT

[Caideyipi]

Description

IoTDBSessionRelationalIT.dropTableOfTheSameNameTest assumes that DROP TABLE finishes deletion before returning. With asynchronous deletion, the next query can receive 555: ... pre-delete state instead of the expected 550: Table 'db2.table16' does not exist.

Poll the existing table-not-found assertion with Awaitility for up to 60 seconds, using the session's thread and closing any successful query result while waiting. Check that the same-named table in db1 retains its original data after the db2 table is gone. A deletion that never completes still fails the test.

Validation

• mvn spotless:apply -pl integration-test -Pwith-integration-tests passed (scoped to the changed file).
• mvn package -DskipTests -pl integration-test -am -Pwith-integration-tests -Ddevelocity.off=true passed, rebuilding the test nodes and compiling the integration tests. Checkstyle and Spotless passed during the build.
• mvn failsafe:integration-test@integration-test failsafe:verify@verify -pl integration-test -PTableSimpleIT -Pwith-integration-tests -Dit.test=IoTDBSessionRelationalIT#dropTableOfTheSameNameTest -DfailIfNoTests=true -Ddevelocity.off=true passed: 1 test, 0 failures/errors/skips (1 ConfigNode, 1 DataNode).
• The same targeted Failsafe command with -PTableClusterIT passed: 1 test, 0 failures/errors/skips (1 ConfigNode, 3 DataNodes).

Local Maven runs used a bounded heap (-Xmx2048m for packaging and -Xmx1024m for Failsafe) and -XX:ActiveProcessorCount=4. The full verify lifecycle was stopped when RAT stalled scanning local Git ignore rules; the package build and targeted Failsafe verification above completed successfully.

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This PR has:

• been self-reviewed.
• added comments explaining the intent of the code.
• modified an existing integration test.
• been tested in a test IoTDB cluster.

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Key changed classes

• IoTDBSessionRelationalIT