Investigate Astro middleware on Cloudflare Workers

### Description

It seems that the Astro middleware is not working properly when running on Cloudflare Workers. This was found when checking against Astro 6 on Cloudflare [a lot of attributes got dropped](https://github.com/getsentry/sentry-javascript/commit/bb891e6cef64c3cbc2adea4a402a69d85ed03963).

We need to investigate and double check if this `addMiddleware` is getting added on Cloudflare Workers: https://github.com/getsentry/sentry-javascript/blob/bb891e6cef64c3cbc2adea4a402a69d85ed03963/packages/astro/src/integration/index.ts#L241-L244