Add flag com.android.graphics.surfaceflinger.flags.deprecate_vsync_sf to trunk_staging.

This change was automatically created by advancing the Gantry workflow at:
https://releasetracker.partner.android.com/changes/bqelda2000001?build_unique_id=android_platform_core_graphics
Do not edit this file manually or revert this change - use the Gantry workflow to manage the state of this flag.

Bug: 162235855
Flag: com.android.graphics.surfaceflinger.flags.deprecate_vsync_sf
Ignore-AOSP-First: AConfig change for future AOSP release
Change-Id: I04254bb3a33516efd8acdf3beeda0ae530b1dbd1