Synchronize listeners in ConfigurationControllerImpl

An array was being modified at the same time it was being copied.
This causes nulls to be copied into the new destination, resulting in
unexpected NPEs when accessed.

Flag: NA
Test: NA
Fixes: 280463030
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:349c46c498eeca75823d1853057193f60595db04)
Merged-In: I6752fbd677a63e72f16edcaebb678a4272432e3b
Change-Id: I6752fbd677a63e72f16edcaebb678a4272432e3b