Migrate mc18 HI test to mc21, using ttbar and removing hijing from HITtoRDO step.
This is a workaround for ATR-27107 until new HI HITS files are available which can work in 23/master. Also relevant for ATLASRECTS-7555
This is a workaround for ATR-27107 until new HI HITS files are available which can work in 23/master. Also relevant for ATLASRECTS-7555