Set min application service stream_id to 1

Factored out into #12193.

synapse/storage/databases/main/appservice.py

@@ -446,7 +446,7 @@ class ApplicationServiceTransactionWorkerStore(
             )
             last_stream_id = txn.fetchone()
             if last_stream_id is None or last_stream_id[0] is None:  # no row exists
-                return 0
+                return 1
             else:
                 return int(last_stream_id[0])
 

tests/storage/test_appservice.py

@@ -476,12 +476,12 @@ class ApplicationServiceStoreTypeStreamIds(unittest.HomeserverTestCase):
         value = self.get_success(
             self.store.get_type_stream_id_for_appservice(self.service, "read_receipt")
         )
-        self.assertEqual(value, 0)
+        self.assertEqual(value, 1)
 
         value = self.get_success(
             self.store.get_type_stream_id_for_appservice(self.service, "presence")
         )
-        self.assertEqual(value, 0)
+        self.assertEqual(value, 1)
 
     def test_get_type_stream_id_for_appservice_invalid_type(self) -> None:
         self.get_failure(