Fixes #7498

In #6968, sub tracks splitting has been fixed but not entirely, if the
user wants to import tracks between more than 2 jobs it can cause
malformed annotation like #7498.

In the pervious test case,
https://github.com/opencv/cvat/blob/d1a300f0189744bef01d2c60135ec474c5004fbc/tests/python/rest_api/test_tasks.py#L543-L563
skeleton track is static so it did not identify any issues.

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### Motivation and context
Pervious interpolate method will drop the last frame. That's correct for
most cases, but if slices and tracks are like this:

slice: -------------xxxxx---------
track: ---------xxxxxxxxxx-------

We have to keep the last frame of slice in the track. If not, this track
won't close.

### How has this been tested?
I rewrited the testcase `test_can_split_skeleton_tracks_on_jobs`
Now it test the split function with a longer input track and stricter
interpolate reference.

### Checklist
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- [x] I have increased versions of npm packages if it is necessary

([cvat-canvas](https://github.com/opencv/cvat/tree/develop/cvat-canvas#versioning),

[cvat-core](https://github.com/opencv/cvat/tree/develop/cvat-core#versioning),

[cvat-data](https://github.com/opencv/cvat/tree/develop/cvat-data#versioning)
and

[cvat-ui](https://github.com/opencv/cvat/tree/develop/cvat-ui#versioning))

### License

- [x] I submit _my code changes_ under the same [MIT License](
https://github.com/opencv/cvat/blob/develop/LICENSE) that covers the
project.
  Feel free to contact the maintainers if that's a concern.

---------

Co-authored-by: Maxim Zhiltsov <zhiltsov.max35@gmail.com>