Investigate multithreading options passed to LHCbApp and Gaussino

The following discussion from !912 (merged) should be addressed:

• @mimazure started a discussion:

  These are multi-threading options that are set both for LHCbApp and Gaussino. Both of these configurables sets up the AvalancheSchedulerSvc. I think that we should not pass these options to LHCbApp and rely solely on Gaussino, but for some reason it does not work as expected. This needs more investigation.