Make sure temporary CI deployments are removed

We are creating temporary deployments in our CI runs and they don't get removed if the CI run was interrupted. E.g. if a new commit was pushed to a PR, or the run was cancelled manually, between deployment and withdrawal.

Find a way to cleanup the runs automatically.

GitHub doesn't support action cleanup. So, perhaps something like a separate service running in the Google Cloud's staging project where we deploy our PRs could get informed about each deployment and delete them after a timeout.

Start by tracing how CI deployments are created and withdrawn in the Google Cloud staging project, then review how interrupted or cancelled runs can be detected. Done means temporary deployments are automatically removed after interruption or a defined timeout, including when a new commit replaces a PR run.

Written by the indexing model from the issue text.