DO NOT MERGE ANYWHERE: Deprecate QNS network disable reason BAD_LINK

WifiNetworkAgent#unwanted no longer disables the network.

Note: this CL is a cherry-pick of ag/1292017, as that CL cannot be
submitted until after N DR cutoff date (expect submission on 8/18).

Bug: 28558417
Change-Id: I2e7ed99ae4cb952f124c673376d967eeee2b4ece
(cherry picked from commit 7d82f98b)