UPSTREAM: <carry>: remove uneed image builds.

MLMD GRPC and Envoy image builds are no longer needed since we
leveragage service mesh and MR's images respectively.

Signed-off-by: Humair Khan <HumairAK@users.noreply.github.com>

.github/workflows/build-images.yaml

@@ -81,10 +81,6 @@ jobs:
             dockerfile: backend/Dockerfile.persistenceagent
           - image: ds-pipelines-scheduledworkflow
             dockerfile: backend/Dockerfile.scheduledworkflow
-          - image: ds-pipelines-metadata-grpc
-            dockerfile: third_party/ml-metadata/Dockerfile
-          - image: ds-pipelines-metadata-envoy
-            dockerfile: third_party/metadata_envoy/Dockerfile
           - image: ds-pipelines-driver
             dockerfile: backend/Dockerfile.driver
           - image: ds-pipelines-launcher