Simplify IsIndexUsableForReplicaIdentityFull()
Take Relation as argument instead of IndexInfo. Building the
IndexInfo is an unnecessary intermediate step here.
A future patch wants to get some information that is in the relcache
but not in IndexInfo, so this will also help there.
Discussion: https://www.postgresql.org/message-id/
333d3886-b737-45c3-93f4-
594c96bb405d@eisentraut.org