Fix screen timeout override not work

Using 'PowerManagerInternal.isInteractive()' to check the interactive
state.

Also add a new ScreenTimeoutOverridePolicyTest.

Bug: 399578561
Test: PowerServiceTests
Flag: com.android.server.power.feature.flags.enable_early_screen_timeout_detector

Change-Id: Ia97c1c66fb9134b5e4e6166a35b684dcaa5b634a