Use the right API in vacuum TINC test to wait until database is up

Otherwise the test would prematurely determine that all segments are up after
PANIC and move on.  This is causing intermittent failure in CI.

src/test/tinc/tincrepo/mpp/gpdb/tests/storage/vacuum/scenario/test_faults.py

@@ -59,18 +59,10 @@ class scenario_fault(MPPTestCase):
 
     def check_connection(self):
         '''
-        Wait till the system is up, as master may take some time
+        Wait till the system is up, as master/segments may take some time
         to come back after FI crash.
         '''
-        up = False
-        for i in range(60):
-            res = PSQL.run_sql_command('select 1', flags='-A -t')
-            if res.strip() == '1':
-                up = True
-                break
-            time.sleep(1)
-
-        self.assertTrue(up, 'database has not come up')
+        PSQL.wait_for_database_up()
 
 class vacuumFaultsTest(MPPTestCase, ScenarioTestCase):
     '''