Remove storm_catalog schema

Remove storm_catalog schema

The storm_catalog schema is supposed to contain the same catalogs and
views as pg_catalog, but filtered to the current database. The use case
for this is multi-tenant systems, which was a StormDB feature.

But on XL this is mostly irrelevant, and the schema was not populated
since commit 8096e3edf17b260de15472eb04567d1beec1e3e6 which disabled
this part of initdb.

So instead of fixing the regression failures in misc_sanity caused by
this (initdb-time schema with no pinned objects), just rip all the
remaining bits out, including the pgxc_catalog_remap GUC etc.

This also removes the setup_storm() call disabled by 8096e3edf1, as the
function got removed since then.