Fix TINC gpactivatestandby negative test

The gpactivatestandby utility was recently changed in commit
https://github.com/greenplum-db/gpdb/commit/c42035ea6089ad9f447f2780b90e7b53413d5e7c
to disable some validations on master data directory. The commit was
merged without running this test and made our CI pipeline red... so
here's the test fix to update expected error handling stdout.

src/test/tinc/tincrepo/mpp/gpdb/tests/storage/walrepl/run/test_gpactivatestandby.py

@@ -57,8 +57,11 @@ class gpactivatestandby(StandbyRunMixin, MPPTestCase):
                 'gpactivatestandby -a -d invalid_directory')
         cmd.run()
         results = cmd.get_results()
-        expected = 'Current setting of MASTER_DATA_DIRECTORY not same as -d parameter'
+        expected = 'Please make sure the command gpactivatestandby is executed on current Standby host'
+        expected_regex = 'Error activating standby master: Critical required file on standby \".*\" is not present'
+
         self.assertIn(expected, results.stdout)
+        self.assertRegexpMatches(results.stdout, expected_regex)
         self.assertEqual(results.rc, 2)
 
     def test_from_not_running(self):