The original function did extensive calculations to get the nearest handle,
even though none of the calling functions used that information.
Its functionality was very similar to `mouseover_strips_sorted_get`, except
that it was less precise and did not factor in `STRIP_OFSBOTTOM/OFSTOP`.
`mouseover_strips_sorted_get` is called by
`ED_sequencer_pick_strip_and_handle`, so update all of the calling functions to
use this instead.
Refactor and replace `find_nearest_seq` into `mouseover_strip_get`, which does
not factor in padded strip handles, and is used only by
`ED_sequencer_special_preview_set` as a static function for scrubbing over
strips.
Pull Request: https://projects.blender.org/blender/blender/pulls/133744
cc97c55515