Remove separator line above error card

Screenshots attached to the bug.

Bug: 341237198
Change-Id: If345778ab25a3507dd653a440e2c268874144921
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5607667


Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Mahmoud Rashad <mmrashad@google.com>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1311971}