Clean up PATs::ExpiringWorker extended logging

What does this MR do and why?

Clean up PATs::ExpiringWorker extended logging

We have not hit any of the unusual edge cases we added logging for here, and have stopped receiving internal reports of duplicate expiry emails.

This cleans up the extended logging code added to PersonalAccessTokens::ExpiringWorker in !174791 (merged)

References

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• Bug issue: #506438 (closed)
• MR introducing the extended logging: !174791 (merged)
• FF rollout issue: #509375 (closed)

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