Google Cloud Pub/Sub streaming support

Unfortunately, the current implementation is quite old and reference dependencies with CVE.

The existing provider also is not automatically tested; making the updating process dangerous, especially since we don't have in-house experience with Google Cloud Pub/Sub.

The plan is to remove it from the repo. But if someone wants to revive it, with up-t-date dependencies and automated tests, then feel free to revert the deletion PR (#9031), and start from there.

Start with the deletion plan in PR #9031 and inspect the existing Google Cloud Pub/Sub provider and its outdated dependencies. Reviving the support would require current dependencies and automated tests; the work is complete when the provider is safely maintained and tested.

Written by the indexing model from the issue text.