Add tracking when auto banning users

What does this MR do and why?

This adds tracking when users are auto-banned because they tried to identify with a phone number or credit card that belongs to a previously banned user:

• write the event to the application log
• track the event in sisense
• record a custom attribute for the banned user

Issue: https://gitlab.com/gitlab-org/modelops/anti-abuse/team-tasks/-/issues/369

How to set up and validate locally

1. From the console run the following

   Users::AutoBanService.new(user: User.last, reason: :banned_phone_number).execute

2. Verify the custom attributes on that user's detail page now show something like

   

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.