Transform UnipipeServiceBroker to Stateless Architecture

[DorukAkinci]

Our current Unipipe-service-broker solution needs a local storage to store the temporary git changes and then it merges(pushes) them into the remote repo. This cycle makes our OSB eventually consistent.

This solution does not handle temporary storages well enough and if we want to use Serverless services like (GCP Cloud Run) we should improve how our OSB works on the backend side.

The serverless approaches are so fast to initialize and it is also so cheap because it only costs when it is active.

We should consider a way to use cloud storages or some other solution.

[DorukAkinci]

Additional Info: The CloudRun service sends a SIGTERM signal before shutting down the containers. Our application can handle these signals to gracefully shutdown itself.
https://cloud.google.com/run/docs/reference/container-contract#instance-shutdown