Cookie controls: Fix animation triggering logic

This CL fixes the cookie controls animation logic:

- Cookie controls icon should be animated when an high breakage
confidence level is reported, regardless of the third-party cookies
deprecation status. The trigger can happen at any time, also after the
page finished loading, so moving this part close to its callback.

- WebContents should be updated only when the tab changes. We're
currently updating the webcontents each time the url changes and this
conflicts with the backend logic, where an high confidence level is
triggered when N reloads happen in a certain amount of time T ([1] and
[2]).

[1]http://shortn/_N9rnXceC28
[2]http://shortn/_PhMvKudF6F

Bug: 1504798
Change-Id: I51e69afe8e6aee474f72e78e494aaf71cf1a8569
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5053989
Commit-Queue: Nicola Tommasi <tommasin@chromium.org>
Reviewed-by: Patrick Noland <pnoland@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1230199}