Placeholder text in Package Manager text fields becomes editable text when navigating empty search field with arrow keys

Steps to reproduce:

1. Create and open a new project
2. Open Window -> Package Management -> Package Manager
3. Press on the "+" menu
4. Select the "Install package from git URL" option
5. Press the left arrow key
6. Observe the text field

Actual results: The placeholder text becomes editable

Expected results: The placeholder text stays uneditable

Reproducible with versions: 6000.6.0a2 (64de5ee36373), 6000.6.0a5

Not reproducible with versions: 6000.0.75f1, 6000.3.16f1, 6000.4.8f1, 6000.5.0b9, 6000.6.0a1

Tested on (OS): Windows 11 Pro (25H2)

Notes:

• Reproducible with all "+" menu items that have text fields