Bar chart update & according legend change

I had to make another update to the bar chart rasterizer for the titles and axis captions to be rasterized in a variable braille level (in this case german kurzschrift). I know that we are supposed to only make changes directly relevant to the issue, but it would cost much time to make 2 extra MRs and so i used the opportunity to fix the checkstyle issues and make the according changes to the legend, so that it displays the correct title and also made the legend title prefix "Legende:" variable by config, because it was hardcoded before.

The changes are small, so I hope it is ok.