add option to create no extra file when processing histogramPlots

Release notes

Adds an option histogramPlotsToExtraFile to the visualize configuration. If set to false, specifying a config file for the histogramPlots option does not cause an additional set of plots to be created.

Details

With the histogramPlots option of the visualize config file, one can fine-tune single plots. When doing so, a third set of plots (in addition to the default lin/log) plots is created. However, except for the choice of lin/log, all three sets use identical configuration (see CommonAnalysisHelpers/python/visualize.py, lines 609ff. In some cases, this may be a good idea, in others, this is superfluous. For the latter case, this MR makes it possible to disable the creation of the third set of plots, but by default, they are created.