Fix PackageInfoUserFieldsTest ClassNotFoundException

In order to make parsing package APIs visible for mainline, moving
parsing classes to system server. The related test cases should
change appropriately. Test Plan should also follow the change.

Because com.android.server.pm.parsing.PackageInfoUserFieldsTest has
been removed , frameworks/base/core/java/android/os/TEST_MAPPING
contains '"include-filter":
"com.android.server.pm.parsing.PackageInfoUserFieldsTest"'
that doesn't work.

Test: atest \
 com.android.server.pm.parsing.PackageInfoUserFieldsTest;
 # It gets Class Not Found
Test: http://ab/I11400010010682351

Fixed: 215305254
Change-Id: Ib435e5d08faa663dcfd03232378998b1db6f2a0e