ValidPersonOrTeamCache should be a materialized view

ValidPersonOrTeamCache used to be a materialized view maintained by triggers. We had to replace it with a standard view when we split the DB into multiple replication sets. We have since consolidated things back into a single replication set so this change can be reverted. This will speed up the many queries that join with the view.

ValidPersonCache can be updated at the same time.

The alternative is to embed the 'valid person' logic into the queries that need it. This is problematic though as our definition of a 'valid person' could change or be dropped altogether, leaving us with many call sites to update and no easy way of identifying them.