Check return code cvmfs_config at the end of installation

[petricm]

The return code of cmvfs_config setup should be checked in the action as it is not the last command in the setup-cvmfs.sh script.

[petricm]

I just realized there are situations like this

Reading package lists...
E: Failed to fetch http://cvmrepo.web.cern.ch/cvmrepo/apt/dists/bionic-prod/InRelease  403  Forbidden [IP: 137.138.31.235 443]
E: The repository 'http://cvmrepo.web.cern.ch/cvmrepo/apt bionic-prod InRelease' is not signed.
Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package cvmfs
Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package cvmfs-config-default
# cvmfs default.local file installed with cvmfs-contrib/github-action-cvmfs
CVMFS_CLIENT_PROFILE='single'
CVMFS_QUOTA_LIMIT='15000'
CVMFS_USE_CDN='yes'
Run cvmfs_config setup
sudo: cvmfs_config: command not found

which the action just passes through, while it should fail.

[petricm]

and I think we should re-tag this into v2

[vvolkl]

Yes, I'll update the tag