* galera_kill_applier : we should make sure that node has
  correct number of wsrep appliers
* galera_bad_wsrep_new_cluster: This test restarts both nodes,
so it is bad on mtr. Make sure it is run alone
* galera_update_limit : Make sure we have PK when needed
galera_as_slave_replay : bf abort was not consistent
* galera_unicode_pk : Add wait_conditions so that all nodes
are part of cluster and DDL and INSERT has replicated before
any further operations are done.
* galera_bf_abort_at_after_statement : Add wait_conditions
to make sure all nodes are part of cluster and that DDL
and INSERT has replicated. Make sure we reset DEBUG_SYNC.