MDEV-25307: The value of the auto-increment variables changes during the test

The auto-increment variables may change intermittently during
the execution of some tests from the Galera mtr suite, causing
these tests to fail. This patch creates conditions in which
unpredictable changes to these variables are not possible
during the execution of those tests in which this problem
is noticed or their values are restored before the end of
testing.

mysql-test/suite/galera/disabled.def

@@ -14,7 +14,6 @@ MW-328A : MDEV-22666 galera.MW-328A MTR failed: "Semaphore wait has lasted > 600
 MW-328B : MDEV-22666 galera.MW-328A MTR failed: "Semaphore wait has lasted > 600 seconds" and do not release port 16002
 MW-329 : MDEV-19962 Galera test failure on MW-329
 galera_as_slave_replication_bundle : MDEV-15785 OPTION_GTID_BEGIN is set in Gtid_log_event::do_apply_event()
-galera_binlog_stmt_autoinc : MDEV-19959 Galera test failure on galera_binlog_stmt_autoinc	
 galera_concurrent_ctas : MDEV-24842 Galera test failure on galera_concurrent_ctas
 galera_gcache_recover_manytrx : MDEV-18834 Galera test failure
 galera_mdl_race : MDEV-21524: galera.galera_mdl_race MTR failed: query 'reap' succeeded - should have failed with errno 1213

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

+connection node_1;
+connection node_2;
 SELECT @@global.wsrep_sst_auth;
 @@global.wsrep_sst_auth
 ********

mysql-test/suite/galera/t/galera_binlog_stmt_autoinc.cnf

+!include ../galera_2nodes.cnf
+
+[mysqld.1]
+auto_increment_offset=1
+
+[mysqld.2]
+auto_increment_offset=2

mysql-test/suite/galera/t/galera_var_sst_auth.cnf

@@ -5,8 +5,3 @@ wsrep_sst_auth=root:
 
 [mysqld.2]
 wsrep_sst_auth=root:
-
-
-
-
-

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

 --source include/galera_cluster.inc
 --source include/have_innodb.inc
 
+# Save original auto_increment_offset values.
+--let $node_1=node_1
+--let $node_2=node_2
+--source include/auto_increment_offset_save.inc
+
 #
 # MDEV-10492: Assertion failure on shutdown when wsrep_sst_auth set in config
 #
@@ -30,4 +35,5 @@ SELECT @@global.wsrep_sst_auth;
 --source include/wait_condition.inc
 SELECT @@global.wsrep_sst_auth;
 
-
+# Restore original auto_increment_offset values.
+--source include/auto_increment_offset_restore.inc