Revert^2 "[legacy sf flag] - Remove legacyFrontEndEnabled"

This reverts commit ce6bde8dfa93038dd1063bae10b1f83eb1bc7e97.

Reason for revert: b/337894453 is now fixed and the original changes from ag/27000992 should no longer cause a regression in arc.PlayStore.betty_vm

Change-Id: I888a16b3137ba8f81d19b89c8ff291f4adf7d601
5 files changed