Revert "[iOS] Add EG tests for feed header IPH"

This reverts commit 7296ffe6161eb122bafa2d2a35bab743f7c28abc.

Reason for revert: cause test failures on ios-simulator-noncq, e.g.:
https://ci.chromium.org/ui/p/chromium/builders/ci/ios-simulator-noncq/31870/overview

Original change's description:
> [iOS] Add EG tests for feed header IPH
>
> Bug: 1413744
> Change-Id: I19d1315fab77a69756119eafb605c76d3acbdc23
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4234138
> Reviewed-by: Sergio Collazos <sczs@chromium.org>
> Commit-Queue: Adam Arcaro <adamta@google.com>
> Cr-Commit-Position: refs/heads/main@{#1103260}

Bug: 1413744
Change-Id: I977724cf584a716de3c321fe8ec8bb28cc137638
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4237447
Auto-Submit: Phillis Tang <phillis@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Phillis Tang <phillis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1103496}