add: log error when db-schemas config contain restricted schemas

We don't allow accessing schemas "pg_catalog" and "information_schema".
Instead of silently failing requests on these schemas, this now adds
logging an error on startup when these schemas are found in `db-schemas`
config.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

test/io/fixtures/fixtures.yaml

@@ -237,3 +237,7 @@ specialhostvalues:
   - '*6'
   - '!6'
   - '*'
+
+restrictedschemas:
+  - 'pg_catalog'
+  - 'information_schema'