Donot trigger c7 container multinode job on stable/train

This job was kept initially to maintain coverage on c7, since
there is no user of CentOS-7 train, so we are removing this
job.

A periodic version of the job will be still running in the
upstream infra, https://review.opendev.org/#/c/752029/

Since https://review.opendev.org/#/c/752220/ already removes
the same job but it got triggered as it is defined in job
templates, so removing stable/train branch part from job
fixes it.

Added tripleo-ci-centos-8-content-provider to fix job
freeze issue.

Change-Id: I3ed7e99b7bc27094ab4347a4f883afc3787e422e
Signed-off-by: Chandan Kumar (raukadah) <chkumar@redhat.com>

zuul.d/layout.yaml

@@ -8,14 +8,12 @@
     templates:
       - tripleo-ci-build-containers-jobs
       - tripleo-ci-buildimage-jobs
-      - tripleo-multinode-baremetal-full
       - tripleo-multinode-branchful
       - tripleo-multinode-container-full-pipeline
       - tripleo-multinode-experimental
       - tripleo-standalone-scenarios-pipeline
       - tripleo-undercloud-jobs
       - tripleo-periodic
-      - tripleo-multinode-tripleoci
     check:
       jobs:
         - openstack-tox-linters

zuul.d/multinode-jobs.yaml

@@ -604,7 +604,7 @@
 - job:
     name: tripleo-ci-centos-7-containers-multinode
     parent: tripleo-ci-base-multinode
-    branches: ^(stable/(pike|queens|rocky|stein|train)).*$
+    branches: ^(stable/(pike|queens|rocky|stein)).*$
     vars:
       nodes: 1ctlr
       featureset: '010'

zuul.d/periodic.yaml

@@ -2,6 +2,7 @@
     name: tripleo-periodic
     periodic:
       jobs:
+        - tripleo-ci-centos-8-content-provider
         - tripleo-ci-centos-8-containers-multinode:
             vars:
               force_non_periodic: true