pkg/tracing: HTTPStatusCodeAttributes: remove use of deprecated SemConv const

pkg/tracing: HTTPStatusCodeAttributes: remove use of deprecated SemConv const

The "http.status_code" attribute was deprecated in [SemConv v1.21] in favor
of "http.response.status_code", and the `HTTPStatusCodeKey` const was deprecated
in [SemConv v1.22].

The `HTTPStatusCodeAttributes` utility doesn't appear to be used currently, but
let's update it to use both the old and new variants in case someone still uses
it.

[SemConv v1.21]: https://github.com/open-telemetry/opentelemetry-go/blob/v1.38.0/semconv/v1.21.0/attribute_group.go#L106-L114
[SemConv v1.22]: https://github.com/open-telemetry/opentelemetry-go/blob/v1.38.0/semconv/v1.22.0/attribute_group.go#L1444-L1452

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>