MDEV-15811 Fix and re-enable test galera.galera_pc_ignore_sb

* After killing one galera node with include/kill_galera,
  wait for cluster to shrink

* Remove unnecessary include/wait_until_connected_again.inc

mysql-test/suite/galera/disabled.def

@@ -31,4 +31,3 @@ galera_var_retry_autocommit : MDEV-15794 Test failure on galera.galera_var_retry
 galera_var_auto_inc_control_on : MDEV-15803 Test failure on galera.galera_var_auto_inc_control_on
 query_cache : MDEV-15805 Test failure on galera.query_cache
 galera.MW-44 : MDEV-15809 Test failure on galera.MW-44
-galera.galera_pc_ignore_sb : MDEV-15811 Test failure on galera_pc_ignore_sb

mysql-test/suite/galera/t/galera_pc_ignore_sb.test

@@ -20,6 +20,9 @@ SET GLOBAL wsrep_provider_options = 'pc.ignore_sb=true';
 --source include/kill_galera.inc
 
 --connection node_1
+--let $wait_condition = SELECT VARIABLE_VALUE = 1 FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_size'
+--source include/wait_condition.inc
+
 CREATE TABLE t1 (f1 INTEGER) ENGINE=InnoDB;
 INSERT INTO t1 VALUES (1);
 DROP TABLE t1;
@@ -37,10 +40,8 @@ SET GLOBAL wsrep_cluster_address = '';
 
 --connection node_2
 --source include/start_mysqld.inc
---source include/wait_until_connected_again.inc
 
 # Restore original auto_increment_offset values.
 --source include/auto_increment_offset_restore.inc
 
 --source include/galera_end.inc
-