features: do not drop ceilometer when using grenade

We are introducting Ceilometer upgrade process in Grenade:
https://review.openstack.org/#/c/94468/

This patch delete the "ceilometer service remove" when deploying
devstack-gate in a grenade environment.

Change-Id: Id96331d31b67ea8c669a1bb784dc6c1696d2c320
Merge "features: do not drop ceilometer when using grenade"