Silence unknown PostgreSQL OIDs warnings

What does this MR do and why?

When Rails scans a PostgreSQL table, it may come across column types it does not recognize and log a warning the first time. As discussed in https://github.com/rails/rails/issues/40687#issuecomment-733989424, Rails only registers types available to users (https://www.postgresql.org/docs/13/datatype.html).

We can silence these warnings by registering the OIDs in question manually.

Relates to #24043 (closed)

How to set up and validate locally

Run Postgresql::ReplicationSlot.lag_too_great? in a console.

Before

[1] pry(main)> Postgresql::ReplicationSlot.lag_too_great?
  TRANSACTION (0.2ms)  BEGIN /*application:console,db_config_name:main,line:/lib/gitlab/database/schema_cache_with_renamed_table.rb:25:in `columns'*/
unknown OID 28: failed to recognize type of 'xmin'. It will be treated as String.
unknown OID 3220: failed to recognize type of 'restart_lsn'. It will be treated as String.
  Postgresql::ReplicationSlot Exists? (1.0ms)  SELECT 1 AS one FROM "pg_replication_slots" LIMIT 1 /*application:console,db_config_name:main,line:/app/models/postgresql/replication_slot.rb:11:in `block in in_use?'*/
  TRANSACTION (0.2ms)  COMMIT /*application:console,db_config_name:main,line:/lib/gitlab/database.rb:292:in `commit'*/
=> false

After

[1] pry(main)> Postgresql::ReplicationSlot.lag_too_great?
  TRANSACTION (0.2ms)  BEGIN /*application:console,db_config_name:main,line:/lib/gitlab/database/schema_cache_with_renamed_table.rb:25:in `columns'*/
  Postgresql::ReplicationSlot Exists? (1.0ms)  SELECT 1 AS one FROM "pg_replication_slots" LIMIT 1 /*application:console,db_config_name:main,line:/app/models/postgresql/replication_slot.rb:11:in `block in in_use?'*/
  TRANSACTION (0.2ms)  COMMIT /*application:console,db_config_name:main,line:/lib/gitlab/database.rb:292:in `commit'*/
=> false

gitlabhq_development=#  SELECT oid, typname FROM pg_type where oid IN (28, 1034,  194, 3220);
 oid  |   typname
------+--------------
   28 | xid
  194 | pg_node_tree
 1034 | _aclitem
 3220 | pg_lsn
(4 rows)

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