fix: don't cp tracking_geometry.obj in central_electrons.sh

This PR removes the expectations to have tracking_geometry.obj produced by the Acts geometry conversion.

benchmarks/tracking/central_electrons.sh

@@ -126,6 +126,3 @@ if [[ "${JUGGLER_N_EVENTS}" -lt "500" ]] ; then
     cp ${JUGGLER_REC_FILE} results/.
   fi
 fi
-
-cp tracking_geometry.obj results/.
-