Controls UI - Remove stale references to prevent memory leak

The binding controller uses callbacks to other areas of code to convey
subscriber changes. Since this area uses a binder, GC may not happen
immediately. Therefore, reassign callbacks when complete.

Fixes: 160305530
Test: external/perfetto/tools/java_heap_dump -n com.android.systemui
Change-Id: I6e4811dca8cb4eb5a3d75d5707bea611c5ce613b