Add additional meaningful information for standalone hosts in AWS

[LDiazN]

Sometimes we get an obscure alert with the style: [FIRING] monitoringproxy.prod.ooni.io:9200 had 1 OOMs in 5m that looks like it came from the monitoring proxy, but in this case it came from a cluster instance.

We want to update the ECS discovery script to add additional information about hosts behind AWS

The task is:

• Look into what other useful information can we get from the ECS discovery script
• Add this information as labels
• Change alerts to include this information in the alert body (the message we see on slack)