MDEV-31173 : Server crashes when setting wsrep_cluster_address after adding invalid value to wsrep_allowlist table

Problem was that wsrep_schema tables were not marked as
category information. Fix allows access to wsrep_schema
tables even when node is detached.

This is 10.4-10.9 version of fix.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>