ATR-17662 : Remove legacy minbias ART tests in master.
They don't work and won't be fixed as focus is on AthenaMT developments
deleted: Trigger/TrigValidation/TriggerTest/test/test_slice_minbias_build.sh
deleted: Trigger/TrigValidation/TriggerTest/test/test_slice_minbias_grid.sh
deleted: Trigger/TrigValidation/TriggerTest/test/test_slice_minbias_hmt_build.sh
deleted: Trigger/TrigValidation/TriggerTest/test/test_slice_minbias_hmt_grid.sh