Add a test for metered/non-metered mobile network am: 2685c929f4 am: bbb828ef8e am: 7bd953a52e

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1779527

Change-Id: I0997a3d5e1e69c4cf8f3b1c53c8e46aa45f5ca21