Don't allow upstream if entitlement don't know any downstream

In case tethering donwstream is setup but don't ask EntitlementManager
to run provisioning. Cellular upstream should not be allowed if
EntilementManager don't have any donwstream record.

Bug: 134649258
Test: -build, flash, boot
      -manual test with carrier SIM
Change-Id: I609722c79f0a45a1c2164d39721ef5883e436feb