Add a test for NetworkIdentity.getMetered() am: eaca5b1982 am: 1d79f3dd99 am: 27282130c6 am: 8f74a5b35e

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1779526

Change-Id: Ied8673f9c86c04257296baeebfcfa76849244625