Ceilometer no longer requires its own database since metric/event
storage was offloaded to Gnocchi/Panko. These implementations were
formally deprecated during the previous cycle[1] so can be removed.
This also updates the outdated example manifests to adapt to
the removal and the recent refactoring.
[1] 60882c29dff6b5302d982eaf79796913c4a8bea9
Change-Id: Id18b9221703eda9311b81c5a5dfdd41cc68f5424
834d9a6780