Retire networking-onos, openstack-ux, solum-infra-guest-agent: Step 1

These three repositories have been retired by their projects some time ago [1]:
- openstack-ux: 2017-02-24
- networking-onos: 2016-11-01
- solum-infra-guestagent: 2016-11-24

They have no contribution and are still setup in Zuul, I'll retire them now
following our retirement process [2] and thus remove them from Zuul.

Announcement is done [3].

Links:
[1] https://opendev.org/openstack/governance/src/branch/master/reference/legacy.yaml
[2] https://docs.openstack.org/project-team-guide/repository.html#retiring-a-repository
[3] http://lists.openstack.org/pipermail/openstack-discuss/2020-June/015640.html

Needed-By: https://review.opendev.org/737989
Needed-By: https://review.opendev.org/737988
Needed-By: https://review.opendev.org/737991
Change-Id: I0a53a7655884448c0ab55006ce49fd2825406701

zuul.d/projects.yaml

@@ -3369,30 +3369,8 @@
 - project:
     name: openstack/networking-onos
     templates:
-      - check-requirements
-      - openstack-python-jobs-neutron
-      - publish-to-pypi
-    check:
-      jobs:
-        - openstack-tox-pep8:
-            required-projects:
-              - openstack/networking-sfc
-        - openstack-tox-py27:
-            required-projects:
-              - openstack/networking-sfc
-        - legacy-tempest-dsvm-networking-onos:
-            voting: false
-            irrelevant-files:
-              - ^(test-|)requirements.txt$
-              - ^setup.cfg$
-    gate:
-      jobs:
-        - openstack-tox-pep8:
-            required-projects:
-              - openstack/networking-sfc
-        - openstack-tox-py27:
-            required-projects:
-              - openstack/networking-sfc
+      - official-openstack-repo-jobs
+      - noop-jobs
 
 - project:
     name: openstack/networking-ovn
@@ -4090,7 +4068,8 @@
 - project:
     name: openstack/openstack-ux
     templates:
-      - openstack-specs-jobs
+      - official-openstack-repo-jobs
+      - noop-jobs
 
 - project:
     name: openstack/openstack-virtual-baremetal
@@ -5582,11 +5561,8 @@
 - project:
     name: openstack/solum-infra-guestagent
     templates:
-      - openstack-cover-jobs
-      - openstack-python-jobs
-      - openstack-python35-jobs-nonvoting
-      - check-requirements
-      - publish-to-pypi
+      - official-openstack-repo-jobs
+      - noop-jobs
 
 - project:
     name: openstack/solum-specs