Revert "Revert "Make RollbackPackageHealthObserver observe apk-in-apex""

This reverts commit 400124c6aecf5cfcd06f101d2260c016f3b6cae5.

Reason for revert: Fixed the compile error; TestAppACrashingV2 was not
available to com.android.apex.apkrollback.test_v1

Change-Id: Ic443e913b837c9bb2716678521ad1d12d3bc7e4d

• services/core/java/com/android/server/rollback/Rollback.java[diff]
• services/core/java/com/android/server/rollback/RollbackPackageHealthObserver.java[diff]
• tests/RollbackTest/Android.bp[diff]
• tests/RollbackTest/RollbackTest/src/com/android/tests/rollback/StagedRollbackTest.java[diff]
• tests/RollbackTest/StagedRollbackTest/src/com/android/tests/rollback/host/StagedRollbackTest.java[diff]