feat(meta-service): Add comprehensive snapshot database metrics

[drmingdrmer]

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Summary

feat(meta-service): Add comprehensive snapshot database metrics

Add detailed snapshot database metrics to monitor storage performance and statistics:

• Block count, data size, index size metrics
• Average block size and keys per block calculations
• Block read statistics (total, from cache, from disk)
• Upgrade rotbl dependency to 0.2.7 for enhanced access statistics

These metrics provide visibility into snapshot storage efficiency and cache performance.

All metrics are gauge type:

# number of keys in the last snapshot.
metasrv_server_snapshot_key_count 0

# number of primary keys in the last snapshot.
metasrv_server_snapshot_primary_index_count 0

# number of expire index keys in the last snapshot.
metasrv_server_snapshot_expire_index_count 0

# number of blocks in the last snapshot.
metasrv_server_snapshot_block_count 0

# size of data section in the last snapshot.
metasrv_server_snapshot_data_size 0

# size of index section in the last snapshot.
metasrv_server_snapshot_index_size 0

# average size of a block in the last snapshot.
metasrv_server_snapshot_avg_block_size 0

# average number of keys per block in the last snapshot.
metasrv_server_snapshot_avg_keys_per_block 0

# total number of read block from cache or from disk.
metasrv_server_snapshot_read_block 0

# total number of read block from cache.
metasrv_server_snapshot_read_block_from_cache 0

# total number of read block from disk.
metasrv_server_snapshot_read_block_from_disk 0

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Type of change

• Other

Related Issues

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