Prevent isolated_app from searching system_data_file.

There should be no need for this, and it allows probing for file existence.

Access to /data and more specifically labeled directories under it
(e.g. /data/app) is not affected.

Bug: 158088415
Test: Builds
Change-Id: Iac39629b1c7322dc2fd9a57c9f034cb2ba73793f
2 files changed