fix: Playground shouldn't be run in serverless environment by default

Author: paveltiunov

packages/cubejs-cli/templates.js

@@ -78,7 +78,7 @@ provider:
     CUBEJS_DB_TYPE: ${env.dbType}
     CUBEJS_API_SECRET: ${env.apiSecret}
     CUBEJS_APP: "\${self:service.name}-\${self:provider.stage}"
-    NODE_ENV: "\${self:provider.stage}"
+    NODE_ENV: production
     AWS_ACCOUNT_ID:
       Fn::Join:
         - ""