Revert "Increase font weight when date cell is selected"

This reverts commit d5c34ff7931d74952e9d837bfecda3dacfcf60c9.

Reason for revert: CalendarMonthViewTest.Basics failing on
https://ci.chromium.org/ui/p/chromium/builders/ci/linux-chromeos-rel/57202/overview

Original change's description:
> Increase font weight when date cell is selected
>
> Today date cell selected (before): https://screenshot.googleplex.com/yBccy6yWawAqLVC
> Non-today date cell selected (before): https://screenshot.googleplex.com/BZnf7QCyoKzngJU
> Today date cell selected (after): https://screenshot.googleplex.com/6YBmL5MbRsQeVah
> Non-today date cell selected (after): https://screenshot.googleplex.com/4G2PaegZwrjRAwD
>
> Bug: 1304496,1304497
> Change-Id: I9d328c7dd6da48e99ce6109f43564bbd5fbacd7e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3597539
> Reviewed-by: Jiaming Cheng <jiamingc@chromium.org>
> Commit-Queue: Elliot Tuck <etuck@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1010281}

Bug: 1304496,1304497
Change-Id: If05a391d820893ba7b7e0efad5b594c368d1f335
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3688889
Auto-Submit: Christopher Lam <calamity@chromium.org>
Commit-Queue: Jiaming Cheng <jiamingc@chromium.org>
Reviewed-by: Jiaming Cheng <jiamingc@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1010355}