Remove calls to wsrep_append_fk_parent_table() during REPAIR/OPTIMIZE
TABLE processing. It turns out that REPAIR or OPTIMIZE commands on
table t, do not acquire MDL locks on parent tables of t (as shown in
the included test).  Thus making wsrep_append_fk_parent_table()
unnecessary for OPTIMIZE and REPAIR.
This also fixes MDEV-24446 and reenables test galera.mysql-wsrep#198.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>