Remove apex_available whitelist for the extservices APEX

The marked library(ies) were available to the APEX via the
hand-written whitelist in build/soong/apex/apex.go. Trying to remove the
whitelist by adding apex_available property to the Android.bp of the
libraries.

Bug: 150999716
Test: m
Merged-In: I827d604c7e5a469a8b8a6d5a4b7917f2eaca48ca
Change-Id: I827d604c7e5a469a8b8a6d5a4b7917f2eaca48ca