[AF] Remove unused autofill suggestion limit field trial.

Bug: 841772
Change-Id: I776e01a71231f4fe54fb25a698af0fc74bc95041
Reviewed-on: https://chromium-review.googlesource.com/1129368
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573920}
3 files changed