Fix the broken analytics proxy

[mveytsman]

Describe your changes

When I did #388 I was wondering why that parsers plug stuff was in the router not the endpoint!

I realize I put it in there following this guide: https://github.com/tallarium/reverse_proxy_plug?tab=readme-ov-file#usage-in-phoenix

Before #388 we wouldn't do the MethodOverride plug, which is what lets the frontend have buttons that use the DELETE method (it has a special parameter that MethodOverride turns into a DELETE methoded request).

After #388 we were parsing all requests, including those for the proxy to analytics, so the proxy wouldn't have any body to send when sending post requests.

I've now added a cache for bodies for requests to /analytics/* following the guide linked above

🤞

Checklist before requesting a review

• I have performed a self-review of my code
• If it is a core feature, I have added tests.
• Are there other PRs or Issues that I should link to here?
• Will this be part of a product update? If yes, please write one phrase
  about this update in the description above.