Add job to run Tempest dsvm on MongoDB backend for Ceilometer

This patch adds templates for both smoke and full Tempest
tests executions and enables both of them to the experimental
pipeline for Ceilometer to be able to debug its behavior
in both cases.

Change-Id: I5655dec73616a0b68665115c1406c41397e5e90c
Merge "Add job to run Tempest dsvm on MongoDB backend for Ceilometer"