Compare the behavior of accepting IPv6 link-local DNS

Added a feature flag to turn on/off the behavior of accepting IPv6
link local DNS. It's better to do A/B testing based the exact legacy
code, namely, DNS server string array contains an IPv6 link-local
address string without scope id instead of skipping it.

Bug: 163492391
Test: atest NetworkStackIntegrationTests
(cherry picked from https://android-review.googlesource.com/q/commit:3a354353e1e5219dc7400f2de7b64f0318728d7c)
Merged-In: Ic789e39fd419458adba968263aa3bd032cbe31fa
Change-Id: Ic789e39fd419458adba968263aa3bd032cbe31fa
1 file changed