Update opentelemetry-js semantic conventions which differ from spec

[rdooley]

A few notes here about opentelemetry-js SemanticConventions we are using that differ from spec

• http.request_content_length should be http.request.body.size
• http.status_code should be http.response.status_code
• http.scheme should be url.scheme
• http.user_agent should be user-agent.original

Originally posted by @rdooley in https://github.com/evanderkoogh/otel-cf-workers/issues/53#issuecomment-1728495110

[evanderkoogh]

Am I understanding you correctly that we are using the constants in opentelemetry-js, but that those are not the right ones according to the spec?!

[rdooley]

yes

[evanderkoogh]

I fixed all of those in https://github.com/evanderkoogh/otel-cf-workers/commit/819e313476aca1c9e37f8987dd54b31bdeced6a4