Ensure SDK emits `url.full` attribute on `http.client` spans

[Lms24]

The url.full semantic attribute is missing from http.client spans created by the core fetch instrumentation.

packages/core/src/fetch.ts (getFetchSpanAttributes) sets url, http.url, server.address, http.query, and http.fragment, but it does not set url.full.

This should be added to match the OpenTelemetry semantic conventions and the behavior of the browser fetch instrumentation (packages/browser/src/tracing/request.ts), which already sets url.full.

[linear-code]

JS-3098

[sentry-pierre]

I added the exact file and function to the body so the next person doesn't have to hunt for it.