Removing Centos 7 in favor of Centos 8

This patch converts the Centos 7 jobs to Centos 8 and re-enable
them as non-voting.
It also changes the lower-constraints job to template.

Change-Id: I9d6c8dd59b2c40b5c309dfab0c35cfbfb1197d4e

releasenotes/notes/bionic-centos8-ci-5047b40c6ba51484.yaml

@@ -0,0 +1,6 @@
+---
+other:
+  - |
+    We have removed the CI jobs with Ubuntu Xenial and CentOS 7 in favor of
+    CI jobs with Ubuntu Bionic and CentOS 8.
+

zuul.d/bifrost-jobs.yaml

@@ -46,9 +46,9 @@
     nodeset: ubuntu-bionic
 
 - job:
-    name: bifrost-integration-dhcp-centos-7
+    name: bifrost-integration-dhcp-centos-8
     parent: bifrost-integration-dhcp
-    nodeset: centos-7
+    nodeset: centos-8
 
 - job:
     name: bifrost-integration-dhcp-opensuse-15
@@ -70,9 +70,9 @@
     nodeset: ubuntu-bionic
 
 - job:
-    name: bifrost-integration-dibipa-debian-centos-7
+    name: bifrost-integration-dibipa-debian-centos-8
     parent: bifrost-integration-dibipa-debian
-    nodeset: centos-7
+    nodeset: centos-8
 
 - job:
     name: bifrost-integration-dibipa-debian-opensuse-15
@@ -99,9 +99,9 @@
       enable_keystone: true
 
 - job:
-    name: bifrost-integration-tinyipa-centos-7
+    name: bifrost-integration-tinyipa-centos-8
     parent: bifrost-integration-tinyipa
-    nodeset: centos-7
+    nodeset: centos-8
 
 - job:
     name: bifrost-integration-tinyipa-opensuse-15

zuul.d/project.yaml

@@ -1,13 +1,13 @@
 - project:
     templates:
       - openstack-python3-ussuri-jobs
+      - openstack-lower-constraints-jobs
       - check-requirements
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
     check:
       jobs:
         - bifrost-integration-tinyipa-ubuntu-bionic
-        - openstack-tox-lower-constraints
         # - bifrost-integration-tinyipa-opensuse-15
         # Non-voting jobs
         - bifrost-integration-tinyipa-keystone-ubuntu-bionic:
@@ -16,18 +16,17 @@
             voting: false
         - bifrost-integration-dibipa-debian-ubuntu-bionic:
             voting: false
+        - bifrost-integration-dhcp-centos-8:
+            voting: false
+        - bifrost-integration-dibipa-debian-centos-8:
+            voting: false
+        - bifrost-integration-tinyipa-centos-8:
+            voting: false
         # - bifrost-integration-dhcp-opensuse-15:
         #    voting: false
-        # - bifrost-integration-dhcp-centos-7:
-        #    voting: false
-        # - bifrost-integration-dibipa-debian-centos-7:
-        #    voting: false
         # - bifrost-integration-dibipa-debian-opensuse-15:
         #    voting: false
-        # - bifrost-integration-tinyipa-centos-7:
-        #    voting: false
     gate:
       jobs:
         - bifrost-integration-tinyipa-ubuntu-bionic
-        - openstack-tox-lower-constraints
         # - bifrost-integration-tinyipa-opensuse-15