web,otel: add url to span name

[tatchi]

This PR suggests adding the url to the span name. This is not spec-compliant

HTTP client spans have no http.route attribute since client-side instrumentation is not generally aware of the "route", and therefore HTTP client span names SHOULD be {method}.

But I think it's a nice QOL improvement. We get more information right away, instead of seeing a bunch of lines in Grafana with just the method name.

Showing the full url might be a bit verbose in some cases, I think ideally we should extract the different parts, but that would require parsing the url. And I guess adding a library like uri for this is not desirable?