Add flag com.android.server.display.feature.flags.enable_single_app_event_for_mode_and_frame_rate_override to trunk_staging.

This change was automatically created by advancing the Gantry workflow at:
https://releasetracker.partner.android.com/changes/cattp46000001?build_unique_id=com.android.server.display.feature.flags.enable_single_app_event_for_mode_and_frame_rate_override-platform
Do not edit this file manually or revert this change - use the Gantry workflow to manage the state of this flag.

Bug: 415850294
Flag: com.android.server.display.feature.flags.enable_single_app_event_for_mode_and_frame_rate_override
Ignore-AOSP-First: AConfig change for future AOSP release
Change-Id: I7e0df457e1db5198c934b42bb8818509c3ab73a2