MDEV-24062: Re-disable the test after merge

The test galera.galera_var_replicate_myisam_on
would trigger an assertion failure "mode() == m_local"
in wsrep-lib/src/client_state.cpp after the merge
of commit 3067ffc5 enabled it.

mysql-test/suite/galera/disabled.def

@@ -34,6 +34,7 @@ galera_trigger : MDEV-24048 galera.galera_trigger MTR fails: Result content mism
 galera_var_ignore_apply_errors : MDEV-26770 galera_var_ignore_apply_errors fails Server did not transition to READY state
 galera_var_node_address : MDEV-20485 Galera test failure
 galera_var_notify_cmd : MDEV-21905 Galera test galera_var_notify_cmd causes hang
+galera_var_replicate_myisam_on : MDEV-24062 Galera test failure on galera_var_replicate_myisam_on
 galera_var_retry_autocommit: MDEV-18181 Galera test failure on galera.galera_var_retry_autocommit
 mysql-wsrep#198 : MDEV-24446: galera.mysql-wsrep#198 MTR failed: query 'reap' failed: 2000: Unknown MySQL error
 partition : MDEV-19958 Galera test failure on galera.partition