prci: update fedora used for testing ipa-4-8
    
    * Add nightly definitions to test with latest and previous versions of
      Fedora (30 and 31)
    * Update gating and temp_commit to use the latest Fedora (31)
    * Update templates used to include updated packages
    
    Boxes used:
    * https://app.vagrantup.com/freeipa/boxes/ci-ipa-4-8-f31/versions/0.0.3
    * https://app.vagrantup.com/freeipa/boxes/ci-ipa-4-8-f30/versions/0.0.4
    
    Signed-off-by: Armando Neto <abiagion@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>