Remove dead flag (#37752)

packages/flutter_tools/lib/src/commands/config.dart

@@ -23,7 +23,6 @@ class ConfigCommand extends FlutterCommand {
     argParser.addFlag('clear-ios-signing-cert',
       negatable: false,
       help: 'Clear the saved development certificate choice used to sign apps for iOS device deployment.');
-    argParser.addOption('gradle-dir', help: 'The gradle install directory.');
     argParser.addOption('android-sdk', help: 'The Android SDK directory.');
     argParser.addOption('android-studio-dir', help: 'The Android Studio install directory.');
     argParser.addOption('build-dir', help: 'The relative path to override a projects build directory',
@@ -120,9 +119,6 @@ class ConfigCommand extends FlutterCommand {
       printStatus('Analytics reporting ${value ? 'enabled' : 'disabled'}.');
     }
 
-    if (argResults.wasParsed('gradle-dir'))
-      _updateConfig('gradle-dir', argResults['gradle-dir']);
-
     if (argResults.wasParsed('android-sdk'))
       _updateConfig('android-sdk', argResults['android-sdk']);