Make clusterctl run only on ubuntu

Change-Id: I2c6e2366498cf23ec0fc157738e2e730b65b4f52
diff --git a/jjb/metal3/job_capm3_clusterctl_upgrade_tests.yml b/jjb/metal3/job_capm3_clusterctl_upgrade_tests.yml
index 8dc3fea..12dde54 100644
--- a/jjb/metal3/job_capm3_clusterctl_upgrade_tests.yml
+++ b/jjb/metal3/job_capm3_clusterctl_upgrade_tests.yml
@@ -26,8 +26,8 @@
 
 - job-template:
     id: capm3_clusterctl_upgrade_tests
-    name: '{job_prefix}_{proj}_{capm3_target_branch}_clusterctl_upgrade_test_{image_os}'
-    description: "CAPM3 e2e clusterctl upgrade tests for {org}/{repo} on {image_os}."
+    name: '{job_prefix}_{proj}_{capm3_target_branch}_clusterctl_upgrade_test'
+    description: "CAPM3 e2e clusterctl upgrade tests for {org}/{repo} on ubuntu."
     project-type: pipeline
     defaults: global
     disabled: False
@@ -55,7 +55,7 @@
         description: 'Target branch of the PR'
     - string:
         name: IMAGE_OS
-        default: '{image_os}'
+        default: "ubuntu"
         description: 'Distribution to use for the target host as well as source and target cluster. Can be ubuntu or centos'
     - string:
         name: capm3_release_branch
diff --git a/jjb/metal3/projects.yml b/jjb/metal3/projects.yml
index c410dd1..7adabeb 100644
--- a/jjb/metal3/projects.yml
+++ b/jjb/metal3/projects.yml
@@ -451,6 +451,8 @@
             target_branches:
             - 'release-1.4'
             - 'release-0.3'
+        exclude:
+        - image_os: centos
     - keep_capm3_e2e_integration_tests:
         capm3_target_branch:
         - main: