Temporarily whitelist platform test packages for hidden API

Platform unit tests need to be exempt from hidden API checks but the
APCT infrastructure ignores the corresponding flag in AndroidTest.xml.
Whitelist these packages in ActivityManagerService until the problem
is resolved to allow for hidden API blacklist to be merged.

Bug: 64382372
Bug: 74963051
Test: make
Change-Id: I9480b244dd47bf9c28f41057bdb31717274dd511