chore(bazel): update protobuf to v3.21.3 (#8)

* chore(bazel): update protobuf to v3.21.3

chore(bazel): update gax-java to 2.18.4

PiperOrigin-RevId: 463115700

Source-Link: googleapis/googleapis@52130a9

Source-Link: googleapis/googleapis-gen@6a4d9d9
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiNmE0ZDlkOWJiM2FmYjIwYjBmNWZhNGY1ZDlmNjc0MGIxZDBlYjE5YSJ9

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

packages/google-cloud-apigee-registry/google/cloud/apigee_registry_v1/services/provisioning/async_client.py

@@ -405,9 +405,6 @@ async def sample_delete_instance():
 
                       }
 
-                   The JSON representation for Empty is empty JSON
-                   object {}.
-
         """
         # Create or coerce a protobuf request object.
         # Quick check: If we got a request object, we should *not* have

packages/google-cloud-apigee-registry/google/cloud/apigee_registry_v1/services/provisioning/client.py

@@ -632,9 +632,6 @@ def sample_delete_instance():
 
                       }
 
-                   The JSON representation for Empty is empty JSON
-                   object {}.
-
         """
         # Create or coerce a protobuf request object.
         # Quick check: If we got a request object, we should *not* have