[omnibox] Sort pedal synonym groups after erasing ignore group

This CL fixes a subtle issue in synonym groups loaded from
translation strings (doesn't apply for Values loaded from JSON).
Previously, the group was sorted when loaded, and then the ignore
group synonyms were erased; with this change, the sort is applied
after erasure. This prevents possible erasure of shorter
subsequences of later supersequences.

Fixed: 1287343
Change-Id: Ia21fc403ff507cc6ebb606327f6a6c8afd3ff65f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3389453


Reviewed-by: Angela Yoeurng <yoangela@chromium.org>
Commit-Queue: Orin Jaworski <orinj@google.com>
Cr-Commit-Position: refs/heads/main@{#959313}