Fix for running HION6 with data overlay MC samples
When running HION6 on data overlay MC samples, the BunchCrossingTool used in JetCommon.py has to be configured like for data, since the data overlay AODs are missing relevant metadata expected for MC samples. The change should be transparent for other derivation formats relying on JetCommon.py and running on standard MC samples.
This MR also adds an ART test for running HION6 on data overlay MC samples, which was previously missing.