Remove GCP dependencies

[jleaniz]

Description of the change

This PR removes deprecated Google PSQ/Pubsub code and associated unit tests.

Applicable issues

• fixes #640
• fixes #215 (deprecated)

Additional information

Documentation should be updated on a separate PR.

Checklist

• [X] All tests were successful.
• [X] Unit tests added.
• [ ] Documentation updated.

[jleaniz]

New error reporting code seems to work after testing on a GCP instance

[aarontp]

Wow, that's great, yeah nice to see this getting cleaned out, thanks! Will take a closer look at the PR tomorrow.

[jleaniz]

Manual testing in GCP, Github e2e and Jenkins e2e tests pass.