Add CTS for getTx/RxBytes in TrafficStats am: 549cc56731 am: 34fe3e48e4 am: 2551dc97bc

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1490180

Change-Id: Iea8de06176cffcb0d32dcd63ceb070d887d3706b
tree: 0ce12d67d60adc338b1750545efa55b631a9a4ad
  1. tests/
  2. Tethering/