Remove success logs

Also, we were panic!ing in the Rust codegen whenever there was an
error in the new storage, switch to panic!ing only if the flag
enabling the use of the new value is enabled.

Bug: 312235596
Test: m
Change-Id: Ic15c21a88bb803d89a489c14f91e7fb82114b443
Ignore-AOSP-First: CP afterwards