Alarms target the incorrect dimension

[ryanjjung]

Looking at the alarms created by the recently added monitoring code, it looks like the dimension is incorrect. We see, for example, the "5xx errors" alert targeting a load balancer called app/send-suite-staging-api/app/send-suite-staging-api/1d41aef7f5a84c15. Instead, we would expect app/send-suite-staging-api/1d41aef7f5a84c15. Something is going wrong in the calculation of this value, and it causes "Insufficient Data" problems (because this data really doesn't exist).