Docker: Add default value for env var SE_NODE_GRID_URL (#2876)

Author: VietND96

NodeBase/Dockerfile

@@ -57,6 +57,7 @@ ENV LANG_WHICH=${LANG_WHICH} \
     SE_NODE_BROWSER_VERSION="stable" \
     SE_NODE_PLATFORM_NAME="Linux" \
     SE_NODE_DELETE_SESSION_ON_UI="true" \
+    SE_NODE_GRID_URL="http://localhost:4444" \
 #============================
 # Some configuration options
 #============================