Moving MT Simulation and Digitization ART jobs into a separate package

As discussed in ATLASSIM-4184 if we pre-assign the ART jobs in SimCoreTests and DigitizationTests to run on the ANALY_BNL_LONG queue then the MT jobs fail to start, if we pre-assign them to run on the ANALY_BNL_MCORE queue then only the MT jobs start.
This merge request splits the MT jobs into separate packages. Once this is merged, the SimCoreTests and DigitizationTests packages should be pre-assigned to run on the ANALY_BNL_LONG queue and the SimCoreTestsMT and DigitizationTestsMT packages should be pre-assigned to run on the ANALY_BNL_MCORE queue.