Use nginx default value for SSLECDHCurve

This configuration setting permits nginx to auto discover supported curves based on what openssl was compiled with. With the old default of secp384r1 if you attempted to use a key from a different curve, for example prime256v1, the SSL handshake would fail in an awful way without any helpful errors logged anywhere.

The default setting in nginx has been "auto" since 1.11.0

controllers/nginx/pkg/config/config.go

@@ -411,7 +411,7 @@ func NewDefault() Configuration {
 		ShowServerTokens:           true,
 		SSLBufferSize:              sslBufferSize,
 		SSLCiphers:                 sslCiphers,
-		SSLECDHCurve:               "secp384r1",
+		SSLECDHCurve:               "auto",
 		SSLProtocols:               sslProtocols,
 		SSLSessionCache:            true,
 		SSLSessionCacheSize:        sslSessionCacheSize,