Filter ignored tables and triggers from schema inconsistency reports

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, and the ignore lists move from db.rake into the filter.

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. This changes the metric's value on instances with these triggers. The metric is for troubleshooting and has no performance indicator type, so it keeps its key.

References

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

Screenshots or screen recordings

No UI change. Filtered ExtraTriggers output for the step below:

Before	After
["gitlab_schema_write_trigger_for_users"]	[]

How to set up and validate locally

1. In a Rails console on GDK, add a lock-writes trigger to users and filter the ExtraTriggers result. The transaction rolls the trigger back:

   conn = ApplicationRecord.connection
   validation = Gitlab::Schema::Validation
   
   conn.transaction do
     conn.execute(<<~SQL)
       CREATE TRIGGER gitlab_schema_write_trigger_for_users BEFORE INSERT ON users
         FOR EACH STATEMENT EXECUTE FUNCTION gitlab_schema_prevent_write();
     SQL
   
     database = validation::Sources::Database.new(conn)
     structure_sql = validation::Sources::StructureSql.new(Rails.root.join('db/structure.sql'))
     filter = Gitlab::Database::SchemaValidation::InconsistencyFilter.new(%w[test_replication], ['gitlab_schema_write_trigger_for_'])
   
     inconsistencies = validation::Runner.new(structure_sql, database, validators: [validation::Validators::ExtraTriggers]).execute
     puts inconsistencies.filter_map(&filter).map(&:object_name).inspect
   
     raise ActiveRecord::Rollback
   end

2. It prints []. On master, it prints ["gitlab_schema_write_trigger_for_users"].

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