Read cookie settings directly in "weird" callsites

Namely, IsCookieSessionOnly and ShouldDeleteCookieOnExit, which both
provide a non-null SiteForCookies and an invalid GURL as the
first_party_url -- which is odd.

If we refactor these to read the COOKIES setting directly (which is
what they really want, without any of the cross-site cookies logic),
then we can eventually add a DCHECK that the SiteForCookies and
first_party_url are consistent with each other. This will remove a
footgun, but I'll have to do this as a followup since a bunch of tests
currently fail when I try it.

See related discussion in https://crrev.com/c/5597146.

Change-Id: I41b8f133ce210dcd188d43b86e6cfa4a6f125dd4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6094429
Reviewed-by: Christian Dullweber <dullweber@chromium.org>
Commit-Queue: Chris Fredrickson <cfredric@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1396717}