Fix offset drag and drop in panelled design

What does this MR do and why?

Fix offset drag and drop in panelled design

Uses native drag and drop API rather than Sortable custom implementation

Changelog: fixed

Allows using the Native HTML5 drag and drop API where available to prevent odd behaviour in panel (see 'before' video)

Native HTML5 Drag and Drop has high support, so I don't think this will cause problems: https://caniuse.com/dragndrop

References

Screenshots or screen recordings

Before	After
Screen_Recording_2025-11-13_at_11.03.07	Screen_Recording_2025-11-13_at_11.16.08

How to set up and validate locally

Enable paneled design and check drag and drop functionality where vuedraggable is being used (boards, work item child item widget, etc.)

MR acceptance checklist

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