vcols in the table definition are intentionaly bad and produce
warnings when a table is opened. In some cases (depending on the
TDC/TC state as left by earlier tests) a table might be opened in the
middle of the test, resulting in spurious warnings. Suppress them.

Also, don't run main.mdev-504 for ps-protocol at all (instead of
disabling ps-protocol inside the test, but still running the test)