Popup windows for autocompletion and quick actions overlap with accompanying JavaDoc/Description windows

May be related to #249

## Environment
Eclipse Version: **I20250123-1800 (4.35)** (maybe even in previous versions, I haven't tried)
OS: Windows 10 (haven't tried in other OSes)

## Description
Sometimes the windows that show the JavaDoc of a method (when using method auto-completion) or the description of a quick fix overlap with the other window.

Here you can see it happening with the [auto-completion](https://github.com/user-attachments/assets/518ea931-1d8e-4f15-ac6d-dd76d529ff44) and here with the [Quick Actions `(Ctrl+1)`](https://github.com/user-attachments/assets/63433da6-6503-4938-894e-1f387ea03765).

## To reproduce
Open the auto-completion or the quick actions and play around with the size of the main window. At some point, the secondary window will overlap.

I noticed that the secondary window is pretty smart as where to position/size itself: it usually places itself on the right or below the main window; only when there is little space to the right and bottom of the main window does the secondary window position itself on the left and overlaps the main window.

## Workaround
Making the "main" window (the one with the methods or the actions) smaller lets the "secondary" window (the one with the JavaDoc/Text) adapt to it. The good thing is that the "main" window remembers its size.