Draft: [skip ci] Apply schema inconsistency filter by validator class

What does this MR do and why?

The filter for known schema inconsistencies compared the inconsistency type with names such as extra_tables, but the type is the validator class name. So the ignored test_replication table and the lock-writes triggers (gitlab_schema_write_trigger_for_*) were always reported. The filter now matches the validator classes.

The schema_inconsistencies Service Ping metric now applies the filter before it keeps the first 150 inconsistencies, so these triggers no longer fill the metric.

Split out of !258353 (merged). Related to #632819.

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