Adding flag android.content.pm.improve_install_freeze to trunk_staging.

This change was automatically created by advancing the Gantry workflow at:
https://releasetracker.partner.android.com/changes/ddbpfrc000001?build_unique_id=AndroidContentPmImproveInstallFreezeLaunch-platform
Do not edit this file manually or revert this change - use the Gantry workflow to manage the state of this flag.

Bug: 307561242
Change-Id: I68f5f6cc8d2143ab15520a20bcfe9a6faa20b7a1
Flag: android.content.pm.improve_install_freeze
Ignore-AOSP-First: AConfig change for future AOSP release
1 file changed