Fix a race condition in upstream selection. am: 491999292b am: bf8a7b622d am: 505a805d70

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1662400

Change-Id: I0ac607254e18f3c49c85e5add73eb2122be2dbc0
tree: ec6c0b18e05e0890c3a7a4a62eeb213efac663e0
  1. tests/
  2. Tethering/
  3. .gitignore
  4. OWNERS
  5. PREUPLOAD.cfg
  6. TEST_MAPPING