Fix text not scaling down when system fontScale < 1.0

[kdwkr]

Summary:

Fixes #54168

In React Native 0.82.0, text on Android does not scale down when the system font scale is set to less than 1.0 (e.g., 85%). This regression was introduced when PixelUtil.toPixelFromSP() was changed to use DisplayMetricsHolder.getScreenDisplayMetrics() instead of getWindowDisplayMetrics() in commit 1ad2ec09.

The issue occurs because:

1. windowDisplayMetrics is obtained from context.resources.displayMetrics and includes the system font scale from Configuration
2. screenDisplayMetrics is populated by Display.getRealMetrics(), which returns physical display metrics without the system font scale setting (Reference)

When getRealMetrics() is called, it overwrites the scaledDensity value (which is density * fontScale), effectively resetting it to just density and losing the user's font scale preference.

Changelog:

[ANDROID] [FIXED] - Fix text not scaling down when system fontScale < 1.0

Test Plan:

https://github.com/kdwkr/rn-0.82.0-android-layout-scale
Tested with this reproducer

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[meta-codesync]

@alanleedev has imported this pull request. If you are a Meta employee, you can view this in D85350263.

[meta-codesync]

@alanleedev merged this pull request in 642f086.

[react-native-bot]

This pull request was successfully merged by @kdwkr in 642f086

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