fix: Don't set referrerPolicy on serverside fetch transports

[lforst]

I believe it is pointless (if not harmful) to set the referrerPolicy field on worker runtime fetch transports.

I think we have this because I copy & pasted it at one point from the browser fetch implemetation.

Fixes #9194

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	84.22 KB (-0.03% 🔽)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	31.41 KB (0%)
@sentry/browser - Webpack (gzipped)	22 KB (0%)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	78.78 KB (+0.02% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	28.6 KB (+0.05% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	21.02 KB (+0.07% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	254.47 KB (+0.04% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	86.75 KB (+0.11% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	62.44 KB (+0.16% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	31.47 KB (+0.05% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	84.25 KB (-0.03% 🔽)
@sentry/react - Webpack (gzipped)	22.05 KB (0%)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	102.22 KB (-0.02% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	50.99 KB (-0.01% 🔽)