Fix appsearch filegroups to match package

The "java" directory in appsearch contains both a package structure and
subdirectories that include a package structure. Update the build
structure to match that.

This is part of a chunk of work necessary to avoidi unintentional
classes being included in the public documentation.

Bug: 187386774
Test: diff docs with/without package filter applied
Change-Id: I312d5cef014557b02d5c015899944ffdea8ca168