Use a clean ceilometer sample config file

Copy the sample file from the ceilometer stable/icehouse branch to
remove the manual editions added in our current file.

Using the stable/icehouse branch will make the backport easier.

Change-Id: I1402def0ab529fdcda6c7c5dc373c90cd522cf9d
backport: icehouse
(cherry picked from commit 1a12512f1ca842bfa58977886a1ad6f73c903755)
Merge "Use a clean ceilometer sample config file" into stable/icehouse