[metrics] Add user actions for the scanner in payment methods settings

Note that the user action is already emitting but was forgotten to be
added to the document causing this documentation change-only CL.
https://crsrc.org/c/chrome/android/java/src/org/chromium/chrome/browser/autofill/settings/CreditCardScannerManager.java;l=26-29;drc=b1e3a5cc2ead33904745c2a6c9c87e73c89961cd

Note that the `ApplicationBreadcrumbsNotUserActions` test was updated
to increase the number of not user triggered user actions before
failure (from 200 to 250). This was done because this is the 200th
user action and would fail this test. Determining if the list should
be updated to remove some not user triggered user actions is out of
the scope of this CL.


Bug: 384538322
Change-Id: I3efae7369392f841450487f998398f8167fd3eb0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6383161
Reviewed-by: Jesse McKenna <jessemckenna@google.com>
Commit-Queue: Darwin Yang <darwinyang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1439575}