MDEV-22617 Galera node crashes when trying to log to slow_log table in
streaming replication mode

Other things:
- Changed name of wsrep_after_row(two arguments) to
  wsrep_after_row_internal(one argument) to not depended on the
  function signature with unused arguments.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
	     Added test case