saved_desks: Make the feedback button focus ring follow ChromeVoxxing

Fix the focus ring of the feedback button so that it follows both
tabbing and ChromeVoxxing.

Test: Manual
Bug: 1355589
Change-Id: I977c5b9579dd2c258aa2aa3df629b266b184cbaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3843075


Reviewed-by: Daniel Andersson <dandersson@chromium.org>
Commit-Queue: Yongshun Liu <yongshun@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1041131}