PHOENIX-7846 Bound rotation replay cost for large commit batches

[tkhurana]

Summary

• When a replication log block fills up during append(), the writer implicitly syncs (flushes + closes the block). This change propagates that implicit-sync signal back to ReplicationLog.append() so it can clear currentBatch, acknowledging that all records up to that point are durable.
• Without this fix, log rotation replays the entire inter-sync window (all records since the last explicit sync()) even though most of those records were already durably written via block-full syncs. For large commit batches this means replay cost grows with batch size instead of being bounded by the block size.
• With this fix, rotation replay cost is bounded by the block size regardless of how large the commit batch is.
• The LogFile.Writer.append() return type changes from void to boolean — true when an implicit block-full sync occurred, false when the record was buffered only.

Test plan

• New unit test testBlockFullSyncOnAppendReducesReplayOnRotation in ReplicationLogGroupTest verifies that the number of replayed appends after rotation is strictly less than the total number of records written, confirming block-full clearing bounds replay.
• Existing ReplicationLogGroupTest and ReplicationLogIT suites pass.
• mvn spotless:apply passes.