Internal request metric histograms labeled as nanoseconds are actually seconds

[jszwedko]

While debugging #7371

I found these metrics:

vector_http_client_response_rtt_nanoseconds_bucket{le="-inf",status="200 OK"} 0 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0.015625",status="200 OK"} 10 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0.03125",status="200 OK"} 75 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0.0625",status="200 OK"} 636 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0.125",status="200 OK"} 4130 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0.25",status="200 OK"} 4138 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0.5",status="200 OK"} 4140 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="0",status="200 OK"} 4140 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="1",status="200 OK"} 4144 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="2",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="4",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="8",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="16",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="32",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="32",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="128",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="256",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="512",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="1024",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="2048",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="4096",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="inf",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_bucket{le="+Inf",status="200 OK"} 4151 1620332874288
vector_http_client_response_rtt_nanoseconds_sum{status="200 OK"} 345.1713884290003 1620332874288
vector_http_client_response_rtt_nanoseconds_count{status="200 OK"} 4151 1620332874288

These seem to me to just be seconds rather than nanoseconds which also matches what metrics-rs seems to do with Duration values: https://github.com/metrics-rs/metrics/blob/0df7fe15e4b2b3a415379d59f989adb7881fa323/metrics/src/common.rs#L253

We should audit other places we are reporting Duration values in our metrics to ensure they are properly labeled as seconds.

An alternative is multiply these by 10 * 9 to turn them into nanoseconds. The histogram buckets will need to be updated if we do that.