Update Envoy to 47d09cc (#823)
Update Envoy to 47d09cc (#823)

- Update the `ENVOY_COMMIT` and `ENVOY_SHA` in bazel/repositories.bzl
- .bazelrc already in sync

Signed-off-by: qqustc <599bc1b4e68ce4222dfc048aebd583fa103b6b38@google.com>
envoyproxy/nighthawk,envoyproxy/nighthawk,envoyproxy/nighthawk,envoyproxy/nighthawk