Automated g4 rollback of changelist 158923709.

*** Reason for rollback ***

It's not necessary anymore after we verified it could be controlled from server side.

*** Original change description ***

Flip flag to enable ReturnToCall bubble.

Enables ReturnToCall bubble and changes the name of the flag so that it can be toggled independently from previous versions.

***

Also in the change: Restore TODOs

Test: TH

PiperOrigin-RevId: 159587541
Change-Id: I88f01550f07a7859f41b4f0fc843e92b38f5a85b