Default Brush Dropdown Expands Vertically When Resizing Tile Palette Window Horizontally

Steps to Reproduce:

1. Create a new project
2. Install the "2D Tilemap Editor" package from the Package Manager
3. In the Hierarchy Window, create a Tilemap via 2D Object > Tilemap > Rectangular
4. In the Scene View Overlays, click Open Tile Palette
5. Dock the Tile Palette window beside the Inspector
6. Resize the Tile Palette window from left to right
7. Observe the behaviour of the "Default Brush" dropdown

Actual results: The height of the "Default Brush" dropdown expands and fills the entire section

Expected results: The height of the dropdown remains unchanged, consistent with other dropdowns in the window

Reproducible with versions: 1.0.0 (6000.0.5f1, 6000.0.45f1, 6000.1.0b15, 6000.2.0a9)

Not reproducible with versions: 1.0.0 (2022.3.60f1, 6000.0.4f1)

Tested on (OS): macOS 15.5

Notes: The behaviour of this dropdown should be consistent with the rest of the dropdowns in that window.