Add metric for additional dns query type pref

To be used as a signal of potential enterprise issues with the
HTTPS/INTEGRITY query over Do53 experiments. Recorded at startup, and
as an attempt to create a more useful metric denominator, only recorded
when disabled or when enterprise managed (per the same enterprise
detection as DoH default disabling).

Bug: 1203427
Change-Id: I8b8436919f6816bcbea88bd4f0718caf04a6f3ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3070020


Commit-Queue: Eric Orth <ericorth@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Reviewed-by: Dan McArdle <dmcardle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#908689}