🚀 Add-on CI improvements

[frenck]

Proposed Changes

A couple of CI improvements for the Community add-ons.

• Docker build cache restored from GitHub, no longer takes the ref into account, this allows re-use of the cache in more cases. Lets Docker figures it out (which is what our Dockerfiles are optimized for).
• Applied the same to the deploy, allowing the deploy to use the same cache from the CI.
• Prevents GitHub cache artifacts to grow forever. This is a known issue, however, this PR applies a workaround.
• Fix applied to the label checker, to ensure it works for forked repositories as well.