[Subscription] Bound consensus prefetch memory usage

[Caideyipi]

Description

Bound consensus subscription materialization memory

• Add a dedicated subscription share to query memory. It defaults to about 20% when subscription is enabled, is forced to 0 when disabled, and remains compatible with the legacy eight-part query-memory configuration.
• Enforce one DataNode-wide byte budget across PreparedEntry, realtimeEntriesByWriter, lingerBatch, prefetchingQueue, and inFlightEvents.
• Drain already materialized backlog before converting more WAL entries, and leave blocked data in WAL when no budget is available.

Close lifecycle and ownership races

• Release retained bytes on ACK, seek, close, leader deactivation, fatal-cleanup reconciliation, and recycled-event late ACK paths.
• Prevent a late ACK from an old consumer from stealing an event already claimed by a new consumer.
• Separate initialization and runtime-activation monitors to avoid lock-order inversion, and reject outdated commit contexts after seek/reboot changes.

Regression coverage

• Add wide-table high-throughput tests with a paused consumer and assert materialized memory remains bounded.
• Add coverage for ACK release, deactivation cleanup, recycled-event ownership, oversized entries, and orphaned reservation reconciliation.

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This PR has:

• been self-reviewed.
  • concurrent read
  • concurrent write
  • concurrent read and write
• added comments explaining the why and intent of non-obvious lifecycle code.
• added unit tests for new code paths.

Tested with:

./mvnw -nsu -pl iotdb-core/datanode -am \
  -Dtest=DataNodeMemoryConfigTest,SubscriptionMemoryManagerTest,ConsensusPrefetchingQueueTest \
  test -DskipITs -Dsurefire.failIfNoSpecifiedTests=false

Result: 28 reactor modules succeeded; 29 tests passed; Checkstyle and Spotless passed.

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Key changed/added classes

• DataNodeMemoryConfig
• SubscriptionMemoryManager
• ConsensusPrefetchingQueue
• QueryEngineMemoryMetrics