fix(notifications): include remote server in Docker cleanup messages

[dscamargo]

What is this PR about?

This PR updates Docker cleanup notifications for remote servers to include the server name and ID, making it clear where the cleanup was executed. The server-specific message is now used consistently
across all notification channels.

Confidence Score: 4/5

This PR is not safe to merge until cleanup notices escape server names for each channel.

Summary

• Scheduled cleanup messages include the server name and ID.
• Manual cleanup uses the same server-specific message.
• Email subjects and content now show the supplied cleanup message.

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