Adding backup-and-restore validation group

- editing playbook to add backup-and-restore as group:
  * check-cpu.yaml
  * service-status.yaml
  * validate-selinux.yaml

Depends-on: I6167f65837ba5e96243b20a3661008d1805eedd5
Change-Id: I9428a63327b6b628f9552b6c5ee7f91c8b972508

validations_common/playbooks/check-cpu.yaml

@@ -8,6 +8,7 @@
         Make sure that the server has enough CPU cores.
       groups:
         - prep
+        - backup-and-restore
         - pre-introspection
     minimal_cpu_count: 8
   roles:

validations_common/playbooks/service-status.yaml

@@ -8,6 +8,7 @@
         a failed service.
       groups:
         - prep
+        - backup-and-restore
         - pre-deployment
         - pre-upgrade
         - post-deployment

validations_common/playbooks/validate-selinux.yaml

@@ -6,6 +6,7 @@
       description: >-
         Ensures we don't have any SELinux denials on the system
       groups:
+        - backup-and-restore
         - pre-deployment
         - post-deployment
         - pre-upgrade