Restore the null behavior of buildWifiTemplate

The old behavior was to only return those wifis that have
a null key/subscriber ID (e.g. not carrier wifi). To keep
backward compatibility, restore that behavior.

Also only crash the old methods on devices with initial
SDK U, because it can't be mandated that devices that
upgrade must not call these methods.

Bug: 273963543
Test: FrameworksNetTests
Merged-In: Iefb976ed86a732158964fae38e9e601001c2637a
Change-Id: Iefb976ed86a732158964fae38e9e601001c2637a
1 file changed