fix nginx proxy buffer size

[desainis]

Description

• I believe this will resolve the 502s we're seeing

Resolves:

2024/06/05 18:40:43 [error] 6198#6198: *20870713 upstream sent too big header while reading response header from upstream, client: 10.64.18.187, server: keycloak.dev.terarium.ai, request: "GET /realms/terarium/protocol/openid-connect/auth?client_id=app&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2F%3FconfigHash%3D17975ac7&response_type=code&scope=openid+profile&state=af511483dab9438f8beff8aa04475dbf&code_challenge=U58qWvfW-Z_liFrueCQNpIO5OLQ5zNZMumXpiZoSHUE&code_challenge_method=S256&response_mode=query HTTP/1.0", upstream: "https://10.244.4.112:8443/realms/terarium/protocol/openid-connect/auth?client_id=app&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2F%3FconfigHash%3D17975ac7&response_type=code&scope=openid+profile&state=af511483dab9438f8beff8aa04475dbf&code_challenge=U58qWvfW-Z_liFrueCQNpIO5OLQ5zNZMumXpiZoSHUE&code_challenge_method=S256&response_mode=query", host: "keycloak.dev.terarium.ai", referrer: "http://localhost:8080/"