test(feedback): Re-add feedback CDN tests

[mydea]

This reverts https://github.com/getsentry/sentry-javascript/pull/11888, and ensures the feedback tests actually work on CDN.

For this, we now ensure to serve this locally, so this will work also on release branches. It means you have to use getLocalTestUrl instead of getLocalTestPath to work. (side note: We can/should probably just remove getLocalTestPath overall 🤔 URL based is much more realistic and IMHO better. I'll do that in a follow up, maybe.