Fix avoidBadWifi behavior with IPv6 provisioning

IPv6 provisioning loss should be ignored when avoidBadWifi is false, not
true.

Bug: 139023420
Test: with avoidBadWifi=false, when connected to a mobile hotspot that
      loses connectivity, WiFi does not disconnect anymore
Merged-In: I18dc13083a7af4ed8bf95fbbf7dce0ecb9abaa14
(cherry picked from commit 01d68c56)

Change-Id: I5bea86e0b5733bff7428f0b40c8a6a1907a1e825