Per https://review.openstack.org/#/c/413920/, the ceilometer-collector
service is now deprecated.
This commit removes the inventory group mappings to the
ceilometer-collector service/container. It also removes
the service from the bootstrap and testing inventory.
Relates-To: I396b154d106c0afba44d57792ae6dad39b33a6f5
Closes-Bug: 1666238
Change-Id: Ied14c2a0eda928197c187ad28781568f2d58f51c