Fix Identity update StoreLog under HA

[mkysel]

Take a transaction-scoped advisory lock for identity update StoreLog under HA by calling queries.Queries.AdvisoryLockSequence and switching IdentityUpdateStorer.StoreLog to READ COMMITTED

• Add a new SQLC query AdvisoryLockSequence in identity_updates.sql that invokes pg_advisory_xact_lock using a composite key of node_id and sequence_id.
• Generate code in identity_updates.sql.go including queries.advisoryLockSequence SQL, queries.AdvisoryLockSequenceParams with NodeID and SequenceID, and queries.Queries.AdvisoryLockSequence method to execute the lock.
• Update IdentityUpdateStorer.StoreLog in identity_update_storer.go to use sql.LevelReadCommitted, call querier.AdvisoryLockSequence with IDENTITY_UPDATE_ORIGINATOR_ID and msgSent.SequenceId, and return a non-recoverable error ErrAdvisoryLockSequence on lock failure.

📍Where to Start

Start with the transaction flow in IdentityUpdateStorer.StoreLog in identity_update_storer.go, then review the new SQLC query AdvisoryLockSequence in identity_updates.sql and its generated method in identity_updates.sql.go.

Changes since #1184 opened

• Renamed SQL advisory lock query and generated code from sequence-based to identity-update-specific naming [79cb8de]
• Updated advisory lock method calls in identity update processing [79cb8de]

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Macroscope summarized 79cb8de.

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