Adding flag com.android.trunk_stable_workflow_testing.test_migrate_flag to RELEASE_CONFIG_TRUNKFOOD_STAGING.

This commit was automatically created by advancing a workflow in Gantry. Manual edits to this file are forbidden. If you need to rollback, please visit https://releasetracker.partner.android.com/changes/7l7sd62000001?build_unique_id=Frontend:+android_platform_core_experiments_team_internal,+Study:+ComAndroidTrunkStableWorkflowTestingTestMigrateFlagLaunch to begin a rollback.

POSTSUBMIT ERRORS: If this change breaks postsubmits, please revert it and attach the associated bugs to the reverted CL's description.

Ignore-AOSP-First: AConfig change for future AOSP release

Bug: 319479098
Change-Id: I2a52f633b9053c05b34050dc14f99ac82b96783d