I had to introduce a distinction for both progress bars and progress rings whether the groove is one piece or two:
If it is one piece (F2 and Fusion), we want to draw the full groove below the fill, otherwise it would look strange: (The screenshot below shows the strange behavior that is being avoided with this PR).
If it is two pieces, we need to have a spacing between groove and fill, see the first screenshot above, which we cannot achieve with only one groove bar or arc.
I had to introduce a distinction for both progress bars and progress rings whether the groove is one piece or two: