Add a custom attribute when blocking or unblocking a user

What does this MR do and why?

When an admin blocks or unblocks a user either through the UI or via the API, we now insert or update a custom attribute for the user so that it is easier to find out for T&S who has blocked or unblocked the user.

Issue: #291068 (closed)

Screenshots or screen recordings

The users admin page custom attributes section:

How to set up and validate locally

1. Log in as admin and visit http://localhost:3000/admin/users
2. Block a user
3. Visit http://localhost:3000/admin/users?filter=blocked and unblock the user
4. Visit the users page and scroll down to the custom attributes section

MR acceptance checklist

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