Event-observer http server logging improvements

[zone117x]

The fastify http event server used for observing events from stacks-core needs improved logging. Some logs we had when using Express also no longer show up.

Request completed log

The "request completed" log line isn't very useful by itself. It includes a randomly generated requestID that must be matched against a previous log entry to get the useful details url, request body size, etc.

Example of existing log line:

{"level":"info","time":"2024-10-23T10:24:32.995Z","pid":1,"hostname":"604488d07dce","name":"stacks-node-event","reqId":"req-i3","res":{"statusCode":200},"responseTime":4.694499969482422,"msg":"request completed"}

Unexpected connection termination logging

Log an error/warning when the stacks-node submits an http request and then terminates the http connection before we have replied. Currently there aren't useful logs for when this happens.