Localization: warning box in "Add Custom Locale" does not use the standard HelpBox - its text renders smaller than the Editor default and the message is clipped by a fixed-height box

Steps to reproduce:

1. Create a new project
2. Install the Localization package (com.unity.localization)
3. Open Edit > Project Settings > "App UI", which displays standard HelpBox messages, and note the text size
4. Open Edit > Project Settings > Localization, click "Create", and add the English locale via "Add Locale"
5. Click "Add Custom Locale" and type en in the Locale Identifier field to trigger the warning
6. Compare the warning text size with step 3
7. Read the whole warning sentence - "The Locale Identifier is already being used by X. Using the Same Id may cause conflicts." — and check whether the end of it is cut off or spills outside the box

Actual results: The warning text renders smaller than the Editor default that a standard HelpBox inherits, making it the smallest text in the window. The box does not grow with its content, and the message does not wrap, so the second sentence - the part carrying the actual advice - is clipped or overflows the box

Expected results: The window uses the standard help box, which inherits Editor font settings and grows to fit its content, so the full message is readable and consistent with HelpBoxes elsewhere in Project Settings

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

Tested on (OS): MacBook Pro - Tahoe 26.6.2