Make the codeconv settings uniform (knative-extensions#321)

Author: vagababov

.codecov.yaml

@@ -11,8 +11,14 @@ coverage:
       # only failing because of overall project coverage threshold.
       # See https://docs.codecov.io/docs/commit-status#disabling-a-status.
       default: false
+comment:
+  # Update existing comment or create new if deleted.
+  behavior: default
 ignore:
   - "**/zz_generated*.go" # Ignore generated files.
+  - "**/*.pb.go" # Ignore proto-generated files.
+  - "hack"
   - "pkg/client"
+  - "test"
   - "third_party"
   - "vendor"