chore(db): clarify full-compaction sentinel logging

[EddieHouston]

Summary

Improve RocksDB full-compaction sentinel logging:

• include the database identity in initial-sync compaction messages
• move the routine F-sentinel-found message from INFO to TRACE

Motivation

Each index update checks the full-compaction sentinel for txstore, history, and
cache. Once initial sync has completed, this produced three INFO messages for
every new block.

The initial-sync messages also did not identify which database was being processed,
making the sequential compaction of the three databases look like conflicting
sentinel or trigger transitions.

Behavior

State-changing initial-sync events remain at INFO:

• sentinel missing
• full compaction completed
• triggers tightened
• sentinel set

The steady-state “sentinel found, skipping compaction” path is now logged at
TRACE.

This is a logging-only change. Compaction, trigger, and sentinel behavior is
unchanged.