Summary:
`StatisticsMetricImpl` performance simnifically degraded after https://phorge.dev.yugabyte.com/D39667.
Good news that we use `ScopedStatistics` during read and merge it once with `StatisticsMetricImpl` during read operation.
Could do the same to write operations.

Performance comparison, PgSingleTServerTest.Scan TServer insert time decreased from 12.96s to 12.53s.

Also did the following small improvements:
Removed unnecessary includes of "yb/docdb/docdb_statistics.h", it helped to use `ScopedStatistics` directly in `DocDBStatistics` instead of std::unique_ptr.
Fixed VLOG in ScopedStats, that were collecting dump even when VLOG is off.
Pass operation statistics to `NonBlockBasedFilterKeyMayMatch`, so it works with correct statistics object.
Simplified `FullFilterBitsReader` code.
Jira: DB-14850

Test Plan: Jenkins

Reviewers: esheng

Reviewed By: esheng

Subscribers: ybase, yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D41179