Fix blending kicked fragments from linked list oit

The qt_insertionSort and qt_bubbleSort disagree with the sorting
direction so wrong fragment gets kicked. Fix qt_bubbleSort to sort
same ascending direction as qt_insertionSort.  The final blending
order then needs to be reversed.

The inverse blending was also wrong, so fix that too at the same time.
The srcColor is the colorSum, so it already has the alpha applied, while
the dstColor is the packed fragment, which needs the alpha applied.

Pick-to: 6.12
Fixes: QTBUG-151378
Change-Id: I712098e34e818276772c4763105ed5c3d4a792ac
Reviewed-by: Andy Nichols <andy.nichols@qt.io>