update nentries and idpvm command

As @ncalace suggested, I'm updating our CKF-related ART tests by modifying the IDPVM command ito be closer to what is done in the Athena legacy tests. That means adding a few flags to idpvm.

I'm also increasing the number of processed events for the tt-bar PU200 test (I've specified the sample to be the same as used in https://gitlab.cern.ch/atlas/athena/-/blob/main/InnerDetector/InDetValidation/InDetPhysValMonitoring/test/test_run4_ttbar_PU200.sh). This should simplify the comparison

/cc @adye