Enable vertex time smearing for Run4 simulation (fix ATLSWUPGR-215)

Simulation was so far not including any vertex time smearing. This MR turns it on for Run 4 configurations, where it starts to become relevant for HGTD timing measurements. I guess other detectors might be sensitive to it as well, calorimeters in particular, but I certainly don't want to mess with any Run 3 configuration at this stage, so this is only enabled for Run 4 configuration.

FYI @sch @htorre @dshope @jmasik @tlari @mbandier @wyswys @aleopold