mkcloud: fix install-chef-suse.sh override mechanism
mkcloud: fix install-chef-suse.sh override mechanism

Fix issues with the mechanism for overriding the install-chef-suse.sh
distributed via the crowbar package:

  - mkcloud only works when run from the directory it lives
    in.  (This is arguably a bug, but we can fix it separately
    later.)  That means that you could only override
    install-chef-suse.sh by placing the alternate version in the
    same directory as mkcloud, but this requires an extra copy
    instead of being able to directly test the version in your
    checked out crowbar repo working directory.  It also messes up
    the git repository.

  - The scp was being run even if the override file didn't exist,
    causing a spurious error.

  - The same override code was duplicated.

vmoravec/automation,gosipyan/automation,SUSE-Cloud/automation,aspiers/automation,vmoravec/automation,SUSE-Cloud/automation,aspiers/automation,vmoravec/automation,aspiers/automation,aspiers/automation,gosipyan/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,gosipyan/automation,vmoravec/automation,gosipyan/automation