[views-ax] Migrate kName in ash/login/ui*

This CL migrates the kName attribute in views to be updated
whenever its value should change, rather than querying the value
and computing it only when needed.

The views covered in the CL are:

1)login_error_bubble.cc
2)login_pin_view.cc
3)login_remove_account_dialog.cc
4)pin_request_view.cc

This CL is part of the ViewsAX project:
https://docs.google.com/document/d/1Ku7HOyDsiZem1yaV6ccZ-tz3lO2XR2NEcm8HjR6d-VY/edit#heading=h.ke1u3utej413

Change-Id: I48b72637ca5f5360fa30b3e5e216d00b7892a300
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5823462
Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Commit-Queue: Divyansh Mangal <dmangal@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1352427}