Remove Fedora from the CI

It is currently broken since the only supported version (36) is EOL.
The OpenDev infrastructure will stop supporting Fedora:
https://lists.opendev.org/archives/list/service-discuss@lists.opendev.org/thread/IOYIYWGTZW3TM4TR2N47XY6X7EB2W2A6/

While master branch had a new CI job added to cover netboot,
this change is not being carried back on stable branches in
order to minimize change complexity while focusing on remvoal
of Fedora from CI.

When backporting to Zed, dropped docs changes.

Change-Id: Ie4e67491a62a4c6cb4ca9d6e700cfc226a121235
(cherry picked from commit 16b34f378d)
(cherry picked from commit c5f6c07476)

doc/source/install/index.rst

@@ -25,11 +25,11 @@ Full support (fully tested in the CI, no known or potential issues):
 Limited support, may be removed at any moment:
 
 * Fedora 34 (32+ is supported but not recommended)
+* Ubuntu 20.04 "Focal"
 
 .. note::
    Operating systems evolve and so does the support for them, even on stable
-   branches. This especially concerns Fedora, which is evolving faster than
-   other distributions.
+   branches.
 
 Bifrost structure
 =================

releasenotes/notes/no-fedora-b316bb3147f01166.yaml

@@ -0,0 +1,5 @@
+---
+deprecations:
+  - |
+    Support for Fedora is no longer tested in the CI and will be removed from
+    the code in the near future.

zuul.d/bifrost-jobs.yaml

@@ -139,17 +139,6 @@
     parent: bifrost-integration-tinyipa
     nodeset: debian-bullseye
 
-- job:
-    name: bifrost-integration-tinyipa-fedora-latest
-    parent: bifrost-integration-tinyipa
-    nodeset: fedora-latest
-
-- job:
-    name: bifrost-integration-redfish-uefi-fedora-latest
-    parent: bifrost-integration-tinyipa-fedora-latest
-    vars:
-      test_driver: redfish
-
 - job:
     name: bifrost-tox-linters
     parent: openstack-tox-linters

zuul.d/project.yaml

@@ -17,10 +17,6 @@
         - bifrost-upgrade-ubuntu-focal
         - bifrost-upgrade-keystone-centos9
         # Non-voting jobs
-        - bifrost-integration-tinyipa-fedora-latest:
-            voting: false
-        - bifrost-integration-redfish-uefi-fedora-latest:
-            voting: false
         - bifrost-integration-dhcp-ubuntu-focal:
             voting: false
         - bifrost-integration-dhcp-centos-9: