[StartTablet] Polish the MVT of NTP on tablets.

In this CL, we polish the most recent tiles module on the New Tab Page specifically for tablet devices. We also changed the distance from MVT to the single tab card and the feed section.
See screenshots: https://docs.google.com/document/d/1K1gKFzOiWiolIA4-hke98dLa7sNPpmDaVcEkM0wXC_c/edit?usp=sharing

Low-Coverage-Reason: Some of the changes are tested in instrument test on tablet.
Bug: 1416536
Change-Id: I6cc43e1be188c46f11820d8ac8c317d3f30f7362
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4479149
Reviewed-by: Theresa Sullivan <twellington@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Reviewed-by: Cathy Li <chili@chromium.org>
Commit-Queue: Xinyi Ji <xinyiji@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1144709}