MDEV-20782 : Galera test failure on galera_sr.galera_sr_mysqldump_sst

Add auto increment offset save and restore as node(s) are restarted.

mysql-test/suite/galera_sr/r/galera_sr_mysqldump_sst.result

@@ -10,6 +10,8 @@ SET GLOBAL wsrep_sst_auth = 'sst:';
 connection node_2;
 SET GLOBAL wsrep_sst_method = 'mysqldump';
 connection node_1;
+connection node_2;
+connection node_1;
 CREATE TABLE ten (f1 INTEGER);
 INSERT INTO ten VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
 CREATE TABLE t1 (f1 INTEGER PRIMARY KEY AUTO_INCREMENT, f2 CHAR(255)) ENGINE=InnoDB;

mysql-test/suite/galera_sr/t/galera_sr_mysqldump_sst.test

@@ -7,6 +7,11 @@
 
 --source suite/galera/include/galera_sst_set_mysqldump.inc
 
+# Save original auto_increment_offset values.
+--let $node_1=node_1
+--let $node_2=node_2
+--source suite/galera/include/auto_increment_offset_save.inc
+
 --connection node_1
 CREATE TABLE ten (f1 INTEGER);
 INSERT INTO ten VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
@@ -77,3 +82,6 @@ DROP TABLE ten;
 # with SR, need to disable SR before that.
 SET SESSION wsrep_trx_fragment_size=0;
 --source suite/galera/include/galera_sst_restore.inc
+
+# Restore original auto_increment_offset values.
+--source suite/galera/include/auto_increment_offset_restore.inc