Organize incremental test plan for PackageManager

This patch adds libincfs-test and service.incremental_test in the
presubmit process.

Test: atest service.incremental_test
Test: atest libincfs-test
Test: atest -p system/incremental_delivery/incfs
    http://ab/I24700010005521991

Bug: 180650365
Change-Id: Iaea12556d398893875c4ab3bb928477103fa7c18