Fix handling of non-standard HTTP status codes

[pellared]

Fixes #3902

Also from https://www.rfc-editor.org/rfc/rfc9110.html#section-15-4

HTTP status codes are extensible. A client is not required to understand the meaning of all registered status codes, though such understanding is obviously desirable. However, a client MUST understand the class of any status code, as indicated by the first digit, and treat an unrecognized status code as being equivalent to the x00 status code of that class.

[codecov]

Codecov Report

Merging #3966 (fd266ef) into main (916ae40) will decrease coverage by 0.3%.
The diff coverage is 100.0%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #3966     +/-   ##
=======================================
- Coverage   79.4%   79.1%   -0.3%     
=======================================
  Files        165     165             
  Lines      10426   10293    -133     
=======================================
- Hits        8284    8151    -133     
  Misses      2006    2006             
  Partials     136     136             

Impacted Files	Coverage Δ
...stful/otelrestful/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)
...gonic/gin/otelgin/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)
...rilla/mux/otelmux/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)
...ack/echo/otelecho/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)
...on.v1/otelmacaron/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)
...ace/otelhttptrace/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)
...net/http/otelhttp/internal/semconvutil/httpconv.go	100.0% <100.0%> (ø)

[pellared]

FYI @scorpionknifes

[Aneurysm9]

Also from https://greenbytes.de/tech/webdav/draft-ietf-httpbis-p2-semantics-25.html#rfc.section.6.p.2:

The current STD97 is embodied in RFC9110. Don't think it changes the analysis here, but always good to reference current standards over old drafts.

[codyaray]

Nice, just what we were looking for! Can you cut a new minor release with this? Do you have an ETA?