Split tool - Click and drag to split should keep the existing drag selection colour

### Description

In previous versions when click and dragging to create a split, there was a selection highlight - the same used for regular selection. Some feedback on our upcoming video commented that this didn't visually make sense. I also felt this when using it but forgot to log the issue at the time.

Here is a video of how it should behave.

https://github.com/user-attachments/assets/9840585f-4bee-41da-b6f3-2a34f4090179

Note: this is not a bug that needs to be fixed for alpha. We should fix it for the final release of 4.0.