MDEV-21538: galera_desync_overlapped test result content mismatch

The test has been made more stable according to
the recommendations of the Codership team.

mysql-test/suite/galera/disabled.def

@@ -18,4 +18,3 @@ galera_as_slave_replay : MDEV-32780 galera_as_slave_replay: assertion in the wsr
 galera_slave_replay : MDEV-32780 galera_as_slave_replay: assertion in the wsrep::transaction::before_rollback()
 galera_sst_mysqldump_with_key : MDEV-32782 galera_sst_mysqldump_with_key test failed
 galera_var_ignore_apply_errors : MENT-1997 galera_var_ignore_apply_errors test freezes
-galera_desync_overlapped : MDEV-21538 galera_desync_overlapped MTR failed: Result content mismatch

mysql-test/suite/galera/r/galera_desync_overlapped.result

 connection node_2;
 connection node_1;
 connection node_1;
-CREATE TABLE ten (f1 INTEGER);
+CREATE TABLE ten (f1 INTEGER PRIMARY KEY) Engine=InnoDB;
 INSERT INTO ten VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 CREATE TABLE t1 (f1 INTEGER, PRIMARY KEY (f1)) Engine=InnoDB;
 CREATE TABLE t2 (f1 INTEGER, PRIMARY KEY (f1)) Engine=InnoDB;
@@ -12,6 +12,7 @@ wsrep_desync_count	1
 SET DEBUG_SYNC='before_execute_sql_command SIGNAL alter1 WAIT_FOR alter2';
 INSERT INTO t1 (f1) SELECT 0000 + (100 * a1.f1) + (10 * a2.f1) + a3.f1 FROM ten AS a1, ten AS a2, ten AS a3;
 connection node_1a;
+FLUSH STATUS;
 SET GLOBAL wsrep_desync = 1;
 Warnings:
 Warning	1231	'wsrep_desync' is already ON.

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

@@ -11,7 +11,7 @@
 
 --connection node_1
 
-CREATE TABLE ten (f1 INTEGER);
+CREATE TABLE ten (f1 INTEGER PRIMARY KEY) Engine=InnoDB;
 INSERT INTO ten VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 
 CREATE TABLE t1 (f1 INTEGER, PRIMARY KEY (f1)) Engine=InnoDB;
@@ -24,6 +24,7 @@ send INSERT INTO t1 (f1) SELECT 0000 + (100 * a1.f1) + (10 * a2.f1) + a3.f1 FROM
 
 --connection node_1a
 
+FLUSH STATUS;
 SET GLOBAL wsrep_desync = 1;
 show status like 'wsrep_desync_count';
 SET DEBUG_SYNC='now WAIT_FOR alter1';