Prep the ground for other future use cases of the grace period rollback

This CL changes the eligibility criteria to just the available of a
dtrp value to be considered. This will allow for other use cases such
as CHIPS integrations by partners and other post 3PCD alternatives.

Bug: b:341713763
Change-Id: Ie0f63634edcd42b110646b11a2bd3c549f6e087a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5550056
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Reviewed-by: Anton Maliev <amaliev@chromium.org>
Commit-Queue: Jonathan Njeunje <njeunje@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1303990}