Fork build trigger config and deployment script for custom DC autopush

[hqpho]

• cloudbuild.deploy.yaml -> cloudbuild.push.yaml, which adds a step to update repo version and removes a step to build and push a custom DC image
• deploy shell script -> build-and-deploy shell script, which pulls latest submodules and builds/pushes a new image before deploying.

Once the new trigger flow is fully set up, the old yaml and script can be deleted.