To avoid IP leak from the CreatePermission request, local relay
candidates must not be paired with remote mDNS candidates, per Section
3.3.2 in draft-ietf-rtcweb-mdns-ice-candidates-04.
Bug: webrtc:11038
Change-Id: I13aada79c812712b850293c7e17094dc8f77105a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157340
Commit-Queue: Qingsi Wang <qingsi@webrtc.org>
Reviewed-by: Honghai Zhang <honghaiz@webrtc.org>
Reviewed-by: Alex Drake <alexdrake@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29546}