loki: consider alerts based on log

[llamerada-jp]

What

• Confirm if alerts are needed based on the logs collected by loki and implement it. We had already deployed loki-canary to monitor how to check delay occurred, but set no alert.

How

TBD

Checklist

• [ ] Finish implementation of the issue
• [ ] Test all functions
• [ ] Have enough logs to trace activities
• [ ] Notify developers of necessary actions