#### Summary of Changes
This PR enables perf metrics reporting for RocksDB write-batches.
Samples are reported under "blockstore_rocksdb_write_perf" with op=write_batch
Its cf_name tag is set to "write_batch" as well as each write-batch could include multiple column families.
The sampling rate is still controlled by env arg SOLANA_METRICS_ROCKSDB_PERF_SAMPLES_IN_1K
and its default to 10 (meaning we report 10 in 1000 perf samples).
b84521d47d