CentOS-7 EOL: remove jobs

CentOS-7 went EOL on June 30th. This change removes the job as
mirrorlist.centos.org no longer resolves. Follow-up changes will remove
CentOS-7 from existing elements.

Change-Id: I23a00d2aa2a056dec33516eccb917126f8b766b2

.zuul.d/jobs.yaml

@@ -109,17 +109,6 @@
         base_element: almalinux-container
         release: '9'
 
-- job:
-    name: dib-nodepool-functional-openstack-centos-7-src
-    description: |
-      Test building and booting a Centos 7 image with Nodepool and OpenStack
-    parent: dib-nodepool-functional-src-base
-    vars:
-      nodepool_diskimage:
-        base_element: centos-minimal
-        release: '7'
-        mirror: "http://{{ zuul_site_mirror_fqdn }}/centos"
-
 - job:
     name: dib-nodepool-functional-openstack-centos-8-stream-src
     description: |

.zuul.d/project.yaml

@@ -38,7 +38,6 @@
             voting: false
         - dib-nodepool-functional-openstack-almalinux-9-containerfile-src:
             voting: false
-        - dib-nodepool-functional-openstack-centos-7-src
         - dib-nodepool-functional-openstack-centos-9-stream-src
         # NOTE(rpittau) Fedora 37 is EOL, moving to non-voting for the time being
         # until we move to Fedora 39 or more recent.
@@ -99,7 +98,6 @@
                   label: debian-bookworm
         - opendev-buildset-registry
         - nodepool-build-image-siblings
-        - dib-nodepool-functional-openstack-centos-7-src
         - dib-nodepool-functional-openstack-centos-9-stream-src
         - dib-nodepool-functional-openstack-ubuntu-xenial-src
         - dib-nodepool-functional-openstack-ubuntu-bionic-src