Enable merged search results for Application Dashboard to workaround noise from empty categories
Merge search results in RunnerModel to workaround bug that makes results cluttered by lot of empty categories.
Before:
After:
I would have prefered to restore the behaviour from Plasma 5 where just the empty categories are omitted while the results stay "unmerged" and separated by their category header; but I couldn't figure out how (see https://bugs.kde.org/show_bug.cgi?id=478472#c3 ).
So I'm submitting this workaround, because I think it nevertheless improves the situation a lot compared to the status quo in Plasma 6.