[omnibox] Delimit pedal synonyms with '、' to handle Japanese data

This CL improves translation string parsing by splitting synonym
group data on a comma form sometimes found in Japanese translation
strings.

Fixed: 1287265
Change-Id: I665dcf548bd880c73c3ed4b41dd1138470a27b3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3387839


Reviewed-by: Angela Yoeurng <yoangela@chromium.org>
Commit-Queue: Orin Jaworski <orinj@google.com>
Cr-Commit-Position: refs/heads/main@{#959310}