The code is switching from relying on metadata based groups to
dynamically created groups with add_host.
As such, the group containing gerrit is now 'gerrit'.
Change-Id: I235e445f9e0f7e94f52a0c9dfc0df80b55d49bc1
Remove duplicated tasks line.
This is also reported when runnning: ansible-playbook --syntax-check.
Change-Id: Iad7b205418b57e6f38f2c4851ec2624a93689539