If wait_for_catchup fails under has_wal_read_bug, skip balance of test.

If wait_for_catchup fails under has_wal_read_bug, skip balance of test.

Test files should now ignore has_wal_read_bug() so long as
wait_for_catchup() is their only known way of reaching the bug.  That's
at least five files today, a number expected to grow over time.  This
commit removes skip logic from three.  By doing so, systems having the
bug regain the ability to catch other kinds of defects via those three
tests.  The other two, 002_databases.pl and 031_recovery_conflict.pl,
have been unprotected.  Back-patch to v15, where done_testing() first
became our standard.

Discussion: https://postgr.es/m/20221030031639.GA3082137@rfd.leadboat.com