chore: delete topic after creation (#1687)

chore:delete topic after creation

part of b/470069573

Author: chandra-siri

tests/system/test_notification.py

@@ -60,13 +60,19 @@ def topic_path(storage_client, topic_name):
 @pytest.fixture(scope="session")
 def notification_topic(storage_client, publisher_client, topic_path, no_mtls):
     _helpers.retry_429(publisher_client.create_topic)(request={"name": topic_path})
-    policy = publisher_client.get_iam_policy(request={"resource": topic_path})
-    binding = policy.bindings.add()
-    binding.role = "roles/pubsub.publisher"
-    binding.members.append(
-        f"serviceAccount:{storage_client.get_service_account_email()}"
-    )
-    publisher_client.set_iam_policy(request={"resource": topic_path, "policy": policy})
+    try:
+        policy = publisher_client.get_iam_policy(request={"resource": topic_path})
+        binding = policy.bindings.add()
+        binding.role = "roles/pubsub.publisher"
+        binding.members.append(
+            f"serviceAccount:{storage_client.get_service_account_email()}"
+        )
+        publisher_client.set_iam_policy(
+            request={"resource": topic_path, "policy": policy}
+        )
+        yield topic_path
+    finally:
+        publisher_client.delete_topic(request={"topic": topic_path})
 
 
 @pytest.mark.skip(reason="until b/470069573 is fixed")