MDEV-25718 addendum: stabilization of test success (especially for 11.4+)

Added DEBUG_SYNC_С("ha_write_row_end") in the WSREP branch,
and added a new status to the list of pending statuses in
the mtr test.

mysql-test/suite/galera_sr/t/MDEV-25718.test

@@ -43,7 +43,7 @@ SET SESSION wsrep_sync_wait = 0;
 SET debug_sync = "now SIGNAL write_row_continue";
 
 # Let's give the INSERT some time, to make sure it does rollback
---let $wait_condition = SELECT COUNT(*) = 1 FROM INFORMATION_SCHEMA.PROCESSLIST WHERE INFO = "INSERT INTO t1 VALUES (1)" AND (STATE = "Freeing items" OR STATE = 'Rollback');
+--let $wait_condition = SELECT COUNT(*) = 1 FROM INFORMATION_SCHEMA.PROCESSLIST WHERE INFO = "INSERT INTO t1 VALUES (1)" AND (STATE = 'Freeing items' OR STATE = 'Rollback' OR STATE = 'Query end');
 --let $wait_condition_on_error_output = SELECT INFO, STATE FROM INFORMATION_SCHEMA.PROCESSLIST
 --source include/wait_condition_with_debug.inc
 

sql/handler.cc

@@ -7375,6 +7375,7 @@ int handler::ha_write_row(const uchar *buf)
         ht->flags & HTON_WSREP_REPLICATION &&
         !error && (error= wsrep_after_row(ha_thd())))
     {
+      DEBUG_SYNC_C("ha_write_row_end");
       DBUG_RETURN(error);
     }
 #endif /* WITH_WSREP */