Stop disabling wifi toggle when tethering is restricted

When an admin disallows the user from configuring tethering, the
user should still be able to configure wifi.
When an admin disallows wifi configuration, the behavior is
unchanged: the toggle stays enabled and allows the user to turn
wifi on and off, but clicking on the text results in admin
transparency dialog, so the user won't be able to change wifi
config.

Bug: 149481093
Test: manual with TestDPC as the device owner
Change-Id: I6b33e43901454125c7f3f4dd3c70f050997e4e71