Remove getLastUsedRegularProfile from FaviconHelper.

Bug: 40254448
Change-Id: Id75866d847017813f81b4b26ebf6ba4ce2d23a51
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5464660


Commit-Queue: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Friedrich Horschig <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1289349}