[iOS] Adjust padding between icon and text for KA on tablets

This CL adds the same padding currently used on phones between the
icon and text of a suggestion chip to the tablet suggestion chips.
On phones, this spacing is set on the vertical stack view, but the
tablet version uses an attributed string instead, so the spacing has
been set on the head indent of the paragraph to produce the same
appearance for suggestion chips.

Bug: 385172448
Change-Id: I3b7959d103f1fe3fcc1dd9d38795c4f36827c360
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6387415
Reviewed-by: Noémie St-Onge <noemies@google.com>
Commit-Queue: Alexis Hétu <sugoi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1436834}