strip cluster on/off track dqm@hlt

it was https://github.com/cms-sw/cmssw/pull/4920
The PR was already reviewed but let me ask for my information - a BS check is performed in all the cases and this looks like an unnecessary code repetition. Why don't you move the BS out of the switch statement and check it once (with appropriate error/warning message)? Should it be really different for the first case (above)?  Why do you go with no warning/error here?