Move linting into it's own serial step

This should hopefully reduce test flakiness.

build/Makefile

@@ -102,7 +102,7 @@ build-images: build-controller-image build-agones-sdk-image
 build-sdks: build-sdk-cpp
 
 # Run all tests
-test: ensure-build-image lint test-go test-install-yaml
+test: ensure-build-image test-go test-install-yaml
 
 # Run go tests
 test-go:
@@ -257,7 +257,7 @@ do-release: RELEASE_VERSION ?= $(base_version)
 do-release:
 	@echo "Starting release for version: $(RELEASE_VERSION)"
 	git checkout -b release-$(RELEASE_VERSION)
-	$(MAKE) test
+	$(MAKE) lint test
 	-rm -rf $(agones_path)/release
 	mkdir $(agones_path)/release
 	docker run --rm $(common_mounts) -w $(mount_path)/sdks/cpp $(build_tag) make clean

cloudbuild.yaml

@@ -24,16 +24,19 @@ steps:
 - name: "make-docker"
   dir: "build"
   args: ["pull-build-image"] # pull the build image if it exists
-  id: pull-build-image
+- name: "lint"
+  dir: "build"
+  args: ["lint"] # pull the build image if it exists
+  id: lint
 - name: "make-docker"
   dir: "build"
   args: [ "test" ] # run tests
-  waitFor: ['pull-build-image']
+  waitFor: ['lint']
   id: tests
 - name: "make-docker"
   dir: "build"
   args: [ "build", "push" ] # build all the things, and push images
-  waitFor: ['pull-build-image']
+  waitFor: ['lint']
   id: build
 - name: 'gcr.io/cloud-builders/gsutil'
   dir: "sdks/cpp/bin"