Add user authentication activity metrics

What does this MR do?

This merge request adds additional metrics, that we are going to use to track users' authentication activity.

This could help us to detect problems like https://gitlab.com/gitlab-com/infrastructure/issues/4584 earlier and define new alerts based on these metrics.

Does this MR meet the acceptance criteria?

• Changelog entry added
• Tests added for this feature
• Has been reviewed by a Backend maintainer
• Conforms to the merge request performance guidelines
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes gitlab-org/gitlab-ce#47789