Run2 hbhe noise filter clean up

This is the cleanup version of the Run2 HBHE noise filter.

Compared to previous request (request #5123 ), a few changes are done:
1. Nothing is changed in HLTrigger/Configuration; now used preferred method of existsAs and descriptions
2. Style change following comments from previous request

Thanks,
Yi Chen









Needs to be added to the fillDescriptions method of this plugin as well!