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
Merge "Use a clean ceilometer sample config file"