DPL: Fix bug in o2ParallelWorkflow

The final writer does not need to merge the previous layer
because they are time pipelined.

DPL: adapt document as suggested

o2sim_parallel: correct stack filtering, add timing information

This is providing one more step to be consistent with the serial and parallel
version of the simulation. Up until now, the parallel version did not call
important hooks on the stack object after each event.

Also adding some total timing information to both o2sim and o2sim_parallel
for better systematic comparison.

More complete output from simulation merger; improve sim test stability

* also merge MCTracks + TrackReferences (which where forgotten previously)

* improve simtest stability by writing to distinct sim files (for different tests)

* prepare unit test running the parallel simulation

Disable TRD in G3 test; enable MCH

With the TRD we are getting double free errors at
program exit. Disabling until solved in order to have the CI
clean.

DPL: Fix test_DataRelayer.cxx

Fix uninitialised timeslice field. Only affects the test.

Sync O2RunSim with FairRunSim

After the recent FairRoot bump, I got a crash
which is fixed herewith.

Restore log level parsing logic

Add test for the STATE level too

Restore log level parsing logic

Add test for the STATE level too

Bug and typo fix for coarse electron drift

  o Sectors on the C-side were not processed properly
  o Course -> Coarse