Split slower tests to a separate test target am: 7e5b405961 am: 2cb22712e2 am: 3dbf977064

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2037624

Change-Id: I8c2e8a6d8c6be49f8713cd4304edd89a2409fe31