[iOS] Deprecate traitCollectionWithTraits in ContentSuggestion

Since traitCollectionWithTraits is deprecated in iOS 17,
content_suggestions_tile_layout_util_unittest and
content_suggestions_collection_utils_unittest files were updated to use
the new alternative system, -traitCollectionWithTraits:UITraitMutations.

Bug: 348649285
Change-Id: I3b8d4f856ade6dbc1d944170c1c5d80a062248c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6553065
Commit-Queue: Daniel White <danieltwhite@google.com>
Reviewed-by: Benjamin Williams <bwwilliams@google.com>
Cr-Commit-Position: refs/heads/main@{#1461498}