Re #9543. Add an option to not clear the monitor workspace pointer.

This is particularly required to be able to use this algorithm in the
post-processing step of a live data run. Unless this new property is
set to false, things fail on the second time around because the monitor
workspace has been cleared out of the accumulation workspace.
Merge branch 'feature/9543_accumulate_monitor_data_in_loadlivedata' into develop