Add TrigBjetMonitoring/python/__init__.py

Add TrigBjetMonitoring/python/__init__.py as a possible fix of repeated compilation failure of the package in CI.

• http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/ci/CIWebArea/nicos_web_areaMRCIbuilds64BC7G8AthenaOpt/NICOS_Log_MR-26386-2019-09-06-07-10/Trigger_TrigMonitoring_TrigBjetMonitoring.html
• http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/ci/CIWebArea/nicos_web_areaMRCIbuilds64BC7G8AthenaOpt/NICOS_Log_MR-26330-2019-09-04-17-22/Trigger_TrigMonitoring_TrigBjetMonitoring.html
• http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/ci/CIWebArea/nicos_web_areaMRCIbuilds64BC7G8AthenaOpt/NICOS_Log_MR-26330-2019-09-04-14-16/Trigger_TrigMonitoring_TrigBjetMonitoring.html
• http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/ci/CIWebArea/nicos_web_areaMRCIbuilds64BC7G8AthenaOpt/NICOS_Log_MR-26048-2019-09-05-16-18/Trigger_TrigMonitoring_TrigBjetMonitoring.html