Return correct result

When we find an exemption for another process of the caller app's UID we
need to return that exemption and not the verdict for the caller app.

Test: manual test / atest BackgroundActivityLaunchTest
Bug: 320758929
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:8ed0c0d1dd06d52900ed910a9d1270e406add282)
Merged-In: I838e6d1bd4c1a1b25e206af15075c04eedf93e51
Change-Id: I838e6d1bd4c1a1b25e206af15075c04eedf93e51