Localization: "Locale Name" field in "Add Custom Locale" is pre-filled with the placeholder string "filler text"

Steps to reproduce:

1. Create a new project
2. Install the Localization package (com.unity.localization)
3. Open Edit > Project Settings > Localization and click "Create" to make the settings asset
4. Click "Add Custom Locale"
5. Read the "Locale Name" field without typing anything

Actual results: The field is pre-filled with the literal string filler text. It is an actual field value rather than greyed placeholder text, so clicking "Create" without editing it produces a Locale asset named "filler text"

Expected results: The field starts empty, or shows greyed placeholder text that is not submitted as a value

Reproducible with versions: 1.5.12 (6000.5.7f1, 6000.6.0f1, 6000.7.0a6)

Tested on (OS): MacBook Pro - Tahoe 26.6.2

Notes:

• The string is a real value, not a hint: it survives into the created asset's name and into the "Available Locales" list