Rewrite handling of oob priv-apps in framework.

- Use 'verify' compiler filter for dexopt.
- Don't pass DISABLE_VERIFIER, instead rely on the oat file status.

This is made possible by:
https://android-review.googlesource.com/#/c/platform/art/+/568546/

Which allows loading oat files, but not executing them.

bug: 30972906
Test: build, set pm.dexopt.priv-apps-oob to true, shell stop && start, see we're not
      using the compiled code.

Change-Id: Idb909c68304f74a720499db3a6cc4a457b52f1e1