metrics measuring request duration not generated

Hi, I'm using Menoetius with @hapi/hapi v18.4.1 in Node 10.19.0 and in general is working fine, however I noticed the metrics to measure request duration are not getting populated.

```
# HELP nodejs_version_info Node.js version info.
# TYPE nodejs_version_info gauge
nodejs_version_info{version="v10.19.0",major="10",minor="19",patch="0"} 1

# HELP http_request_duration_milliseconds request duration in milliseconds
# TYPE http_request_duration_milliseconds summary

# HELP http_request_buckets_milliseconds request duration buckets in milliseconds. Bucket size set to 500 and 2000 ms to enable apdex calculations with a T of 300ms
# TYPE http_request_buckets_milliseconds histogram
```

is this expected ? thanks

Start by reproducing the missing request-duration metrics with Menoetius, @hapi/hapi v18.4.1, and Node 10.19.0, then trace where those metrics are registered and observed. Done means determining why the summary and histogram remain empty after requests, or confirming that this behavior is expected.

Written by the indexing model from the issue text.