Return 0 on uninstall when on_master for case of not installed
    
    This is to suppress the spurious error message:
    
    The ipa-client-install command failed.
    
    when the client is not configured.
    
    This is managed by allowing a ScriptError to return SUCCESS (0)
    and have this ignored in log_failure().
    
    https://pagure.io/freeipa/issue/7836
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>