MDEV-30172: Disable galera_sr.MDEV-25718

Author: dr-m

mysql-test/suite/galera_sr/disabled.def

@@ -13,3 +13,5 @@
 GCF-1060 : MDEV-26528 wrong usage of mutex LOCK_thd_kill and LOCK_thd_kill
 galera_sr_cc_master : MDEV-29882 Galera test failure on galera_sr_cc_master
 mysql-wsrep-features#138 : At line 25: query 'DROP TABLE t1' failed: 2013: Lost connection to MySQL server during query
+# Links to below failures in MDEV-30172
+MDEV-25718 : timeout related to wsrep_sync_wait and DEBUG_SYNC