Can we convert metadata tables to reference tables on MX?

@halilozanakgul asked the question whether does it make sense to convert `pg_dist_xx` tables to reference tables and in fact get rid of the metadata syncing.

That might be an idea to consider, though probably once we are comfortable enough with MX by-default on all nodes.

Some things to keep in mind: `Oids`. If there are any OIDs, we should be careful not to sync it. We should try to make sure sending `regclass` type of text.