InDetSLHC_Example: enable flake8 and fix code

InnerDetector/InDetExample/InDetSLHC_Example/CMakeLists.txt

...DetExample/InDetSLHC_Example/python/SLHC_JobProperties.py

...ector/InDetExample/InDetSLHC_Example/python/SLHC_Setup.py

...InDetExample/InDetSLHC_Example/python/SLHC_Setup_ATLAS.py

...nDetExample/InDetSLHC_Example/python/SLHC_Setup_Alpine.py

...mple/InDetSLHC_Example/python/SLHC_Setup_Alpine_ECRing.py

...tExample/InDetSLHC_Example/python/SLHC_Setup_Alpine_VF.py

...etExample/InDetSLHC_Example/python/SLHC_Setup_BeamPipe.py

...tExample/InDetSLHC_Example/python/SLHC_Setup_ExtBrl_32.py

...etExample/InDetSLHC_Example/python/SLHC_Setup_ExtBrl_4.py

...tExample/InDetSLHC_Example/python/SLHC_Setup_IExtBrl_4.py

...DetExample/InDetSLHC_Example/python/SLHC_Setup_InclBrl.py

...mple/InDetSLHC_Example/python/SLHC_Setup_InnerInclined.py

...r/InDetExample/InDetSLHC_Example/python/SLHC_Setup_LoI.py

...Example/InDetSLHC_Example/python/SLHC_Setup_LoI_ECRing.py

...nDetExample/InDetSLHC_Example/python/SLHC_Setup_LoI_VF.py

...r/InDetExample/InDetSLHC_Example/python/SLHC_Setup_XML.py