Run federation jobs on Ubuntu Focal

The packaging issue that was never fixed for Bionic[1] doesn't seem to
be a problem on Focal, so let's switch back to Ubuntu.

[1] https://bugs.launchpad.net/ubuntu/+source/shibboleth-sp2/+bug/1776489

Change-Id: I69b2c650d20e30e35c2388b824cb28fcef2bae77
Depends-on: https://review.opendev.org/726994

.zuul.yaml

@@ -66,6 +66,30 @@
       devstack_localrc:
         IDP_ID: k2k
 
+- job:
+    name: keystone-dsvm-py3-functional-federation-ubuntu-focal
+    parent: keystone-dsvm-functional
+    nodeset: openstack-single-node-focal
+    vars:
+      devstack_localrc:
+        TEMPEST_PLUGINS: '/opt/stack/keystone-tempest-plugin'
+        USE_PYTHON3: True
+      devstack_services:
+        keystone-saml2-federation: true
+        tls-proxy: false
+      devstack_plugins:
+        keystone: https://opendev.org/openstack/keystone
+      zuul_copy_output:
+        /etc/shibboleth: logs
+        /var/log/shibboleth: logs
+
+- job:
+    name: keystone-dsvm-py3-functional-federation-ubuntu-focal-k2k
+    parent: keystone-dsvm-py3-functional-federation-ubuntu-focal
+    vars:
+      devstack_localrc:
+        IDP_ID: k2k
+
 # This job will execute 'tox -e upgrade' from the OSA
 # repo specified in 'osa_test_repo'.
 - job:
@@ -195,10 +219,10 @@
               - ^etc/.*$
               - ^keystone/tests/unit/.*$
               - ^releasenotes/.*$
-        - keystone-dsvm-py3-functional-federation-opensuse15:
+        - keystone-dsvm-py3-functional-federation-ubuntu-focal:
             voting: false
             irrelevant-files: *irrelevant-files
-        - keystone-dsvm-py3-functional-federation-opensuse15-k2k:
+        - keystone-dsvm-py3-functional-federation-ubuntu-focal-k2k:
             irrelevant-files: *irrelevant-files
         - keystoneclient-devstack-functional:
             voting: false
@@ -225,7 +249,7 @@
       jobs:
         - keystone-dsvm-py3-functional:
             irrelevant-files: *irrelevant-files
-        - keystone-dsvm-py3-functional-federation-opensuse15-k2k:
+        - keystone-dsvm-py3-functional-federation-ubuntu-focal-k2k:
             irrelevant-files: *irrelevant-files
         - tempest-full-py3:
             irrelevant-files: *tempest-irrelevant-files

devstack/lib/federation.sh

@@ -82,7 +82,7 @@ function install_federation {
         sudo shib-keygen -f
 
         # Enable the Shibboleth module for Apache
-        sudo a2enmod shib2
+        sudo a2enmod shib
     elif is_fedora; then
         # NOTE(knikolla): For CentOS/RHEL, installing shibboleth is tricky
         # It requires adding a separate repo not officially supported