Nuke f28 job/nodeset definitions

Feora job is deprecated and no longer used anywhere.
f28 image now can be removed from nodepool.

Change-Id: Ic105e2c4533b7b72791fe3ca384cee5e86f20397

zuul.d/deprecated-jobs.yaml

@@ -98,28 +98,3 @@
     vars:
       nodes: 1ctlr
       featureset: '033'
-
-# fedora
-- job:
-    name: tripleo-ci-fedora-28-standalone
-    parent: tripleo-ci-deprecated-standalone
-    nodeset: single-fedora-28-node
-    voting: false
-    branches: ^(?!stable/(newton|ocata|pike|queens|rocky)).*$
-    vars:
-      environment_type: standalone
-      featureset: '052'
-      featureset_override:
-        validate_services: false
-    irrelevant-files:
-      - ^.*\.md$
-      - ^.*\.rst$
-      - ^doc/.*$
-      - ^etc/.*$
-      - ^metadata.json$
-      - ^releasenotes/.*$
-      - ^test-requirements.txt$
-      - ^spec/.*$
-      - ^Puppetfile.*$
-      - tox.ini
-      # like parent but with requirements.txt and setup.py removed

zuul.d/nodesets.yaml

@@ -17,18 +17,6 @@
         nodes:
           - secondary
 
-- nodeset:
-    name: single-fedora-28-node
-    nodes:
-      - name: primary
-        label: fedora-28
-    groups:
-      - name: switch
-        nodes:
-          - primary
-      - name: peers
-        nodes: []
-
 - nodeset:
     name: single-centos-7-node
     nodes: