ci: trigger containerized-tests from GitHub PRs

These additional settings are required to trigger the job to run when a
GitHub PR gets created or updated. It is also possible to manually run
the job by leaving one of the following comments:

    /test ci/centos/containerized-tests
    /retest ci/centos/containerized-tests
    /test all
    /retest all

The 'all' has been added so that future jobs can catch this comment as
well and act on it.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

containerized-tests.yaml

@@ -3,6 +3,15 @@
     name: containerized-tests
     project-type: pipeline
     sandbox: true
+    # TODO: enable 'concurrent' when the pipeline has a re-try on reserving
+    # bare-metal machines
+    concurrent: false
+    properties:
+      - github:
+          url: https://github.com/ceph/ceph-csi
+      - build-discarder:
+          days-to-keep: 7
+          artifact-days-to-keep: 7
     pipeline-scm:
       scm:
         - git:
@@ -18,8 +27,9 @@
     triggers:
       - github-pull-request:
           status-context: ci/centos/containerized-tests
-          trigger-phrase: '^/(re)?test( ci/centos/containerized-tests)?$'
+          trigger-phrase: '/(re)?test ((all)|(ci/centos/containerized-tests))'
           permit-all: true
+          github-hooks: true
           cron: 'H/5 * * * *'
           black-list-target-branches:
             - ci/centos