Improve mtr replication setup

- Log slave state if sync_with_master_gtid fails, like we do
  in sync_with_master.inc
- Increase master-retry-count to 30 for slow builders

mysql-test/include/sync_with_master_gtid.inc

@@ -42,6 +42,7 @@ if ($_result == -1)
 {
   --let $_current_gtid_pos= `SELECT @@GLOBAL.gtid_slave_pos`
   --echo Timeout in master_gtid_wait('$master_pos', $_slave_timeout), current slave GTID position is: $_current_gtid_pos.
+  --source include/show_rpl_debug_info.inc
   --die Failed to sync with master
 }