PAST: Unify callback format to match GD

* So that all periodic sync callbacks are in the same base class

Bug: 229965085
Tag: #gd-refactor
Test: gd/cet/run --sl4a_sl4a
Change-Id: I0e4f1ae81211a48905baf3d3647e9bc4d71b7732
Merged-In: I0e4f1ae81211a48905baf3d3647e9bc4d71b7732
(cherry picked from commit 8ecc9025)