Disable Open in Google Cloud button unless setup is valid
## Context
Part of https://gitlab.com/groups/gitlab-org/-/epics/13124+.
## Problem
Right now we always display the `Open in Google Cloud` button on the artifacts list view, even if there is a problem connecting to GAR:

This can lead to confusion as users may have the required permissions to see the AR repo on the GCP side but then see an error on the GitLab side.
## Proposal
Make the button inactive if unable to list images. Ideally, with https://gitlab.com/gitlab-org/gitlab/-/issues/438560+ we should be able to guard against most misconfiguration errors, but a situation like the one described may still be possible after that.
issue