Refactor CA file handling in replica installer
    
    Clean up and remove obsolete code from ipa-replica-install. For several
    versions replica installer first ensures that a host is an IPA client,
    then promotes the client to a replica. The client installer code sets up
    CA stores like IPA_CA_CRT already.
    
    Related: https://pagure.io/freeipa/issue/9272
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Rafael Guterres Jeffman <rjeffman@redhat.com>
    Reviewed-By: Thomas Woerner <twoerner@redhat.com>