update java local flag read code

This change updates the generated java code for java local flag read.

If the local read happens with in non-updatable framework, then it will
use PlatformAconfigPackageInternal to read the flag value. Otherwise it
will use AconfigPackageInternal to read the flag value.

Test: atest -c
Change-Id: I0f4e233e1e265530cb7cbcca0d1289b6a0211179