Investigate if we can add metrics for HTTP ReadHeaderTimeout for Workhorse
The following discussion from !179305 should be addressed:
- [ ] @ashmckenzie started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/179305#note_2321499325):
> Let's see. From https://ieftimov.com/posts/make-resilient-golang-net-http-servers-using-timeouts-deadlines-context-cancellation/, I see:
>
> 
>
> I got confused between `ReadTimeout` and `ReadHeaderTimeout`. Setting a 90-second `ReadTimeout` had me much more concerned. https://pkg.go.dev/net/http says this:
>
> ```go
> // ReadHeaderTimeout is the amount of time allowed to read
> // request headers. The connection's read deadline is reset
> // after reading the headers and the Handler can decide what
> // is considered too slow for the body. If zero, the value of
> // ReadTimeout is used. If negative, or if zero and ReadTimeout
> // is zero or negative, there is no timeout.
> ReadHeaderTimeout time.Duration
> ```
>
> Yeah, I think 90 seconds **should** be more than enough. I wish we'd be able to see these metrics to get a better idea where we are today.
issue