Add make release

Adds a `make release` command for releasing new NPD version. It stops
pushing the tar files to gs://kubernetes-release, because no one has
write permission to the GCS bucket any more. We haven't pushed NPD tar
files to that GCS bucket after v0.8.10. k/k has been using NPD v0.8.13+
since 1.29. NPD release should just include the tar files in the release
note.

Makefile

@@ -17,7 +17,8 @@
 .PHONY: all \
         vet fmt version test e2e-test \
         build-binaries build-container build-tar build \
-        docker-builder build-in-docker push-container push-tar push clean depup
+        docker-builder build-in-docker \
+        push-container push-tar push release clean depup
 
 all: build
 
@@ -268,8 +269,12 @@ push-tar: build-tar
 	gsutil cp $(TARBALL) $(UPLOAD_PATH)/node-problem-detector/
 	gsutil cp node-problem-detector-$(VERSION)-*.tar.gz* $(UPLOAD_PATH)/node-problem-detector/
 
+# `make push` is used by presubmit and CI jobs.
 push: push-container push-tar
 
+# `make release` is used when releasing a new NPD version.
+release: push-container build-tar
+
 coverage.out:
 	rm -f coverage.out
 	go test -coverprofile=coverage.out -timeout=1m -v -short ./...