gitlab-integration: Use the new name for mgr variant of cephfs

With [1] suffix 'vfs' is irrelevant in 'cephfs.mgr.vfs' as multiple
share configurations are included within mgr variant.

[1] samba-in-kubernetes/sit-environment#117

jobs/gitlab-fs-integration.yml

@@ -2,7 +2,7 @@
     name: samba_gitlab-fs-integration
     file_system:
       - 'cephfs'
-      - 'cephfs.mgr.vfs'
+      - 'cephfs.mgr'
     jobs:
       - 'samba_gitlab-{file_system}-integration'