[iOS][PageInfo] Add field trial config

Bug: 1512580
Change-Id: I8a7e8ac4a2a63a2ca40091b7418cb9e968dc7129
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5392565


Commit-Queue: Filipa Senra <fsenra@google.com>
Reviewed-by: Christian Dullweber <dullweber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1278875}