[cts] use splits for loading progress tests

This mitigates on-device digesters that read all base apk and trigger
full loading.

background.jpg copied from cts/tests/tests/content/HelloWorldApp/

BUG: 181820354
Fixes: 181820354
Test: atest com.android.tests.loadingprogress.host.IncrementalLoadingProgressTest
Change-Id: Ia903fd6708f4e2f46cf6466ad4e3fdbf2c24bd9c
6 files changed