Remove android.icu.... classes from light grey list

Removes all the android.icu.... classes from the light grey lists as
they are now using UnsupportedAppUsage annotation.

This was tested by making and then manually checking that the generated
out/target/common/obj/PACKAGING/hiddenapi-light-greylist.txt was the
same (after sorting) before and after this change.

Test: see above
Bug: 117818301

Change-Id: Ib11d5462580b3698a8b810dc0138642252ec5f18