Clean on demand

Remove all code implementing and referring to the old, by now obsolete, OnDemand Machinary.
Took the opportunity to reduce the size of the SISitripCluster by 4 bytes.

purely technical.
the code removed is not executed anymore (well besides the ifs...)

caveat:
apparently SiStripMonitorMuonHLT and HLTTrackerHaloFilter are broken since 7_1_0 pre3 or pre4.
They got completely unnoticed as apparently are not executed in any workflow
that we run at the moment.
jura issue created https://its.cern.ch/jira/browse/CMSHLT-60