DQM/SiStripMonitorDigi: remove unsued subdetswitchtotdigiproflson

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>