Revert "[ios] Add an Omnibox Position Tips notification"

This reverts commit e6470a0397c24cbb869ed847493f309d1af1ddce.

Reason for revert: Broke Ios-fieldtrial-rel bot.

Original change's description:
> [ios] Add an Omnibox Position Tips notification
>
> This change adds logic to decide whether to send an Omnibox Position
> Tips notification, adds code to show the Omnibox Position view when the
> user interacts with the notification, and adds EG test coverage to
> ensure this UI flow works.
>
> Fixed: 353981779
> Change-Id: Icc4c9800a1e3ff864fd66c8491e9edbb3fc1bf10
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5753149
> Reviewed-by: Christian Xu <christianxu@chromium.org>
> Reviewed-by: Federica Germinario <fedegermi@google.com>
> Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
> Commit-Queue: Scott Yoder <scottyoder@google.com>
> Cr-Commit-Position: refs/heads/main@{#1336569}

Change-Id: I0a63f77d1364678de0603b160e404903142ec318
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5756189
Auto-Submit: Huiting Yu <huitingyu@google.com>
Commit-Queue: Huiting Yu <huitingyu@google.com>
Reviewed-by: Scott Yoder <scottyoder@google.com>
Owners-Override: Huiting Yu <huitingyu@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1336636}