Before this PR the sorting function would receive all FCurves from
the `anim_data` ListBase and sort them + recalculate the handles.
Considering we are already checking
IF an `FCurve` needs sorting we might as well use
that and limit the sorting to FCurves that actually need it.
Doing that gives the following performance uplift.
| - | Before | After |
| - | - | - |
| Moving 1 key only | 109ms | 0.72ms |
| Moving 1 key of each FCurve | ~2000ms | ~2000ms |
Pull Request: https://projects.blender.org/blender/blender/pulls/119735
6a55a126e9