Wired scrollbar click behaviour

### Windows Terminal version

1.20.11781.0

### Windows build number

10.0.22631.4317

### Other Software

_No response_

### Steps to reproduce

Typically when mouse click the scrollbar(not the thumb), hold the mouse button down. The scrollbar will:
page up, , page up, page up, page up, page up,...
Then thumb will stop at the mouse pointer position.

But in the current terminal. There are 3 random behavior.
1. Page up/down once and stop.
2. Thumb not stop. And reach the top/bottom position.
3. Thumb move across the mouse pointer position.

### Expected Behavior

Not random.

### Actual Behavior

see above.

Start by reproducing the scrollbar interaction on Windows Terminal 1.20.11781.0 with Windows 10.0.22631.4317, following the hold-on-scrollbar steps and observing all three outcomes. No source file or test is named, so trace the scrollbar handling from the relevant terminal UI entry point; done means clicks produce one consistent paging and thumb-position behavior.

Written by the indexing model from the issue text.