DQM/SiStripMonitorDigi: remove unsued subdetswitchtotdigiproflson

same as: #5455 
@davidt 


According to UBSan

    DQM/SiStripMonitorDigi/src/SiStripMonitorDigi.cc:275:3

triggers undefined behavior 193 times on full matrix run.

Example workflows:
- 4.68 / step2
- 1309.0 / step3
- 140.52 / step2

This happens before the first even is executed.

After looking into the code the problem is triggered by uninitialized
(?) bool member variable subdetswitchtotdigiproflson used in if
statement. The if statement had an empty body! I cleaned up the source
code by removing all references of subdetswitchtotdigiproflson.
According GIT it's not used anywhere in CMSSW (apart that empty if
statement).

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>