Promotions do not work correctly when using multiple builds-on and runs-on combinations

[simskij]

After running Promote charm from edge to beta, the following happens:

simme@willow:~$ charmcraft status blackbox-exporter-k8s
Track    Base                  Channel    Version    Revision    Resources                                            
latest   ubuntu 20.04 (amd64)  stable     -          -           -                                                    
                               candidate  -          -           -                                                    
                               beta       1          1           blackbox-exporter-image (r1)                         
                               edge       1          1           blackbox-exporter-image (r1)                         
         ubuntu 22.04 (amd64)  stable     -          -           -                                                    
                               candidate  -          -           -                                                    
                               beta       -          -           -                                                    
                               edge       3          3           blackbox-exporter-image (r3)   

Expectation would be for this to happen for both bases. Similarly, the revs do not match between the bases from the get-go.

[lucabello]

Charm promotion happens via the release-charm charming action. The charm release instead happens with the upload-charm charming action.

Both need to be adapted to building and releasing / promoting the charm for all bases.

[simskij]

This is still not solved. Works as intended for publish (upload), but not for promote.