Stop posting config asynchronously.

All of the instances of calling into other services with locks held
should be resolved, so this isn't needed anymore.

Test: have 2 rules end or start at the same time; ensure the resulting
state is correct.

Fixes: 28459870
Bug: 31980467

Change-Id: I3f12f1d3b8460361dab6fa9468f0ede55ca8dd5e
(cherry picked from commit 89aeab0e)