Remove the unused getFlutter function (#55225)

dev/devicelab/lib/framework/utils.dart

@@ -501,30 +501,6 @@ String jsonEncode(dynamic data) {
   return const JsonEncoder.withIndent('  ').convert(data) + '\n';
 }
 
-Future<void> getFlutter(String revision) async {
-  section('Get Flutter!');
-
-  if (exists(flutterDirectory)) {
-    flutterDirectory.deleteSync(recursive: true);
-  }
-
-  await inDirectory<void>(flutterDirectory.parent, () async {
-    await exec('git', <String>['clone', 'https://github.com/flutter/flutter.git']);
-  });
-
-  await inDirectory<void>(flutterDirectory, () async {
-    await exec('git', <String>['checkout', revision]);
-  });
-
-  await flutter('config', options: <String>['--no-analytics']);
-
-  section('flutter doctor');
-  await flutter('doctor');
-
-  section('flutter update-packages');
-  await flutter('update-packages');
-}
-
 void checkNotNull(Object o1,
     [Object o2 = 1,
     Object o3 = 1,