TriggerTest: Fix dry run and command printout in reproducibility test
Two changes are made:
- Bugfix for unit test failure:
http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/gitwww/GITWebArea/nightlies/master/2019-12-19T2131/Athena/x86_64-centos7-gcc8-opt/Athena/UT/TriggerTest.log.html - Improve "command" printout to make it consistent with all other tests