Add logging to the over limit email notification

What does this MR do and why?

Add logging to the over limit email notification

• What: Add logging at a few specific points in the over limit notification code journey.
• Why: Allows us to see count and guage how often this occurs and monitor it when wanted.

See https://gitlab.com/gitlab-org/gitlab/-/issues/415487 for more details

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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

Related to #415487