refs #9048 Coverity noise for UnitsConversionHelper

https://scan6.coverity.com:8443/reports.htm#v29240/p10083/fileInstanceId=11025012&defectInstanceId=3877349&mergedDefectId=529172&eventIds=3877349-17
refs #9048 Coverity noise for LoadMD.cpp

https://scan6.coverity.com:8443/reports.htm#v29240/p10083/fileInstanceId=11026361&defectInstanceId=3878330&mergedDefectId=528984
refs #9048 Coverity noise for UnitsConversionHelper.cpp

https://scan6.coverity.com:8443/reports.htm#v29240/p10083/fileInstanceId=11026361&defectInstanceId=3878330&mergedDefectId=528984
refs #9048 Coverity noise for MDEventsTestHelper.cpp

https://scan6.coverity.com:8443/reports.htm#v29240/p10083/fileInstanceId=11027562&defectInstanceId=3877894&mergedDefectId=528445