[RESTRICT AUTOMERGE] Fix incorrect use of WindowMetrics.density

The API is newly introduced in Android U, but is unexpectedly used for
AOSP master because it has CODENAME of U.

This test would fail internally because Settings use WM Jetpack that
use CODENAME to guard the API before U is finalized.

Bug: 269760296
Test: SafetyCenterActivityTest
      #launchActivity_withFlagDisabled_opensSettings
Change-Id: I2c5c64acfb50de0b27370781ae149c8cf0f87d0f