Table column resizers for last item in group should span all groups

[sroy3]

I thought the resizer would take the whole border when it's the last item of the group since it's the whole group that is resizing. I believe that it was the original behaviour and that it was changed along the way (could be wrong on that one).

https://user-images.githubusercontent.com/3683420/187740873-71586548-402e-4723-a80c-f65b4f77a65b.mov

Originally posted by @sroy3 in https://github.com/iterative/vscode-dvc/pull/2305#pullrequestreview-1092253554