[iOS] Remove all references to ios/c/b/ui

The folder has been cleaned up. This CL removes the last elements in it
and all references to it.

Fixed: 40223315, 40259387
Change-Id: I2fd16e6b032ddb5043e2afe5300eb4f3dc92c06c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6400853
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Robbie Gibson <rkgibson@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1439265}