CI/CD: releasing an RC sets the `latest` tag on quay to said RC

[jecluis]

As shown in the image above, building a Release Candidate resets the latest tag to point to the RC. This is potentially problematic if the RC is not yet in shape to be used by our users.

The latest tag should point to the last released version, which in the current case is still v0.22.0.

I think it would be better if RCs were pushed as a latest-rc instead.

P.S.: quay no longer has the latest tag pointing to the RC -- I've manually reset it to point to v0.22.0.

### Tasks

[jecluis]

This also applies to the UI container