[To dev/1.3] Fence IoTConsensus writes before storage shutdown (#18841, #18893)

[Caideyipi]

Description

Queued IoTConsensus requests can pass the RPC read-only check before shutdown and apply after storage or WAL has stopped, reopening processors and WAL nodes. This backport closes write admission and drains admitted writes, including their WAL separators, before the final flush and storage shutdown.

Cherry-picks:

• 532d6c1 (Fence IoTConsensus applies before storage shutdown #18841)
• d2b97bc (Reuse DataRegion insert lock for IoTConsensus shutdown fencing #18893)

Adaptation for dev/1.3

• Reuse DataRegion.insertLock for admission and WAL separators, keeping memory backpressure and retry waits outside the lock. Apply the same fencing to tree deletions, which already hold the outer visitor lock in 1.3.
• Adapt the 1.3 multi-tablet implementation so the complete admitted batch finishes under the write lock with one WAL separator. Add a regression test for shutdown between tablets.
• Use the 1.3 request, state-machine, and status APIs. Preserve its independent per-request SyncLog status handling.
• Backport the tree-model replication check to pipe.it.autocreate.IoTDBPipeClusterIT. Table-model code and tests do not apply to 1.3.

Validation

• Spotless formatting passed for consensus, datanode, and integration-test.
• Reactor build and targeted tests: mvn -B -nsu test -pl iotdb-core/datanode -am -Dtest=IoTConsensusServerImplTest,IoTConsensusShutdownTest,DataRegionStateMachineTest,DataRegionTest -Dsurefire.failIfNoSpecifiedTests=false -DfailIfNoTests=false -DforkCount=1.
• Result: BUILD SUCCESS; 49 tests passed and 1 existing DataRegion test was skipped. The configured Maven test executions both passed.
• Coverage includes queued writes, the pre-apply race, draining admitted writes and separators, retry waits, memory backpressure, all 1.3 write paths after stop, other consensus protocols, and WAL checkpoint recovery.
• Cluster integration tests were not run locally.

This PR has:

• been self-reviewed, including concurrent writes and shutdown.
• added and adapted regression tests.