Helm: Add ruler endpoint to nginx proxy

[ese]

mimirtool fail to manage rules if you point it to nginx service since it use /api/v1/rules to manage rule operations.

• Make api/v1/rules proxy to ruler service

[dimitarvdimitrov]

That endpoint was removed in #2182 and will be gone in mimir 2.2.0 and helm chart 3.0.0. I'm afraid we can't cherry-pick this into the 2.1. Your option is to copy the nginx configuration into your helm values file and add the route there.