Revert "Compile some ios_chrome_web_egtest files with EG2."

This reverts commit f7f90b374f8a6cb387160b2e8a87cb4429443186.

Reason for revert: crbug.com/968296

Original change's description:
> Compile some ios_chrome_web_egtest files with EG2.
> 
> This CL makes changes to the files, so they either compiled without (or
> with fewer) errors with EG2. Updated EG1 build target with proper EG1
> defined.
> 
> This CL does not add files to EG2 target, because tests are failing
> because of EG2 helper absence.
> 
> Bug: 922813
> Change-Id: I0fbb023d5861405a7324521c0f34f114ec29868e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1632591
> Commit-Queue: Eugene But <eugenebut@chromium.org>
> Auto-Submit: Eugene But <eugenebut@chromium.org>
> Reviewed-by: Rohit Rao <rohitrao@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#663853}

TBR=rohitrao@chromium.org,eugenebut@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 922813
Change-Id: I11bf5065050ce2eb6837001be0ba89472ed1e428
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1636922
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664630}

• ios/chrome/browser/web/BUILD.gn[diff]
• ios/chrome/browser/web/child_window_open_by_dom_egtest.mm[diff]
• ios/chrome/browser/web/error_page_egtest.mm[diff]
• ios/chrome/browser/web/forms_egtest.mm[diff]