[flink] Support remove_orphan_blobs action and procedure.

[Stephen0421]

Purpose

Add Flink remove_orphan_blobs (action + procedure) for unreferenced primary-key .managed.blob packs, stacked on the landed core cleaner and Spark procedure.

• local reuses LocalManagedBlobOrphanFilesClean
• distributed freezes the validated used-pack set with executeAndCollect before listing candidates, then filters with a captured HashSet. Deletion does not reconnect the sidecar/mark DAG, so a lost used-pack shuffle cannot drop a live pack
• Abort if the used-pack set changes (SKIP_MANAGED_BLOB_GC)
• database.* runs tables one after another so one table’s freeze cannot execute another table’s uncommitted deletion graph
• Bounded used/candidate joins keep ALL_EXCHANGES_BLOCKING
• Docs: docs/docs/flink/procedures/repair.md, procedure index, and blob-storage.md

Tests

• RemoveOrphanBlobsActionITCase / RemoveOrphanBlobsActionITCaseBase
  • testDeleteUnreferencedManagedBlobPack
  • testMissingManagedBlobSidecarSkipsPackGc
  • testDistributedDeleteWithEmptyUsedPackSet
  • testDistributedUnresolvableRelativeCandidateSkipsGc
  • testDistributedMarkReadsSharedMetadataOncePerPass
  • testDistributedCleanupDoesNotHangWithPipelinedShuffle
  • testDistributedDeletionAccountingSurvivesCleanupTaskRestartAfterDelete
  • testDistributedCanonicalAliasCandidatesAreCountedOnce
  • testActionFactoryDryRunParsing
  • testActionFactoryRejectsInvalidDryRun
  • testActionFactoryRejectsNonPositiveParallelism
  • testProcedureRejectsNonPositiveParallelism
  • testFrozenUsedMarkIsNotRecomputedDuringDeletion
  • testUsedPackSetChangeSkipsGc
  • testRemoveDatabaseOrphanBlobs
  • testProcedureDryRun
• RemoveOrphanFilesActionITCaseBase
  • testDistributedCleanupForcesBlockingShuffle
• Flink 1.18 / 1.19 subclasses of RemoveOrphanBlobsActionITCase