DEV-899 Adjusted Nginx Ingress Proxy buffers

- Problem with "too big header" from upstream
- There is no annotation for 'proxy_busy_buffer_size'
- Using 'configuration-snippet' instead

values.yaml

@@ -138,5 +138,9 @@ keycloak:
       nginx.ingress.kubernetes.io/backend-protocol: HTTP
       nginx.ingress.kubernetes.io/force-ssl-redirect: "true"
       nginx.ingress.kubernetes.io/ssl-passthrough: "true"
+      nginx.ingress.kubernetes.io/proxy-buffer-size: "128k"
+      nginx.ingress.kubernetes.io/proxy-buffers-number: "4 256k"
+      nginx.ingress.kubernetes.io/configuration-snippet: |
+        proxy_busy_buffer_size: 256k;
       nginx.ingress.kubernetes.io/whitelist-source-range: >-
           212.121.131.106/32,149.233.6.129/32,46.245.219.98/32,164.138.195.162/32,195.201.31.227/32,167.235.150.201/32,167.235.150.198/32,167.235.150.195/32,167.235.150.133/32,167.235.150.197/32,23.88.53.161/32,195.201.113.110/32,5.75.184.216/32,195.201.127.50/32,164.92.251.253/32,91.107.228.133/32,167.235.25.0/32