Revert "Add deprecation issue for Expect-CT header"

This reverts commit 1a1b5a6df86820fbfe5d0598d0e7e98d8f3c6c60.

Reason for revert: Flaky in multiple bots:
https://bugs.chromium.org/p/chromium/issues/detail?id=1345168
https://screenshot.googleplex.com/8qV4ih6bFjUdEnJ

Original change's description:
> Add deprecation issue for Expect-CT header
>
> See https://groups.google.com/a/chromium.org/g/blink-dev/c/bGLVLwSKNJY/m/nbg4hWckAwAJ
>
> Bug: 1232560
> Change-Id: I6e28c40dfa86515331270e0c8b86966642ecec39
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3759196
> Reviewed-by: Mike West <mkwst@chromium.org>
> Reviewed-by: Ari Chivukula <arichiv@chromium.org>
> Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
> Commit-Queue: Emily Stark <estark@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1024828}

Bug: 1232560
Change-Id: Ia7bd65c4d907138f70459d92ec0e9181a0c8f87d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3767016
Auto-Submit: Luciano Pacheco <lucmult@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1025167}