[DoH] Add field trial testing config entry for Quad9Secure

This adds the field trial testing config entry needed to
experiment with enabling the DoH auto-upgrade functionality
for Quad9Secure.

Bug: 1444528
Change-Id: I854f6a852f8ee5d52dabcf645f376b12a61464de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4552836
Reviewed-by: Kyra Seevers <kyraseevers@chromium.org>
Auto-Submit: Andrew Williams <awillia@chromium.org>
Commit-Queue: Kyra Seevers <kyraseevers@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1149737}
NOKEYCHECK=True
GitOrigin-RevId: 12299864d0cb9f6ce7dd11636bcb1aefaea9cc55
1 file changed