enable lint prefer_final_in_for_each (#47724)

diff --git a/packages/flutter_tools/lib/src/run_cold.dart b/packages/flutter_tools/lib/src/run_cold.dart
index 02f95ae..1211452 100644
--- a/packages/flutter_tools/lib/src/run_cold.dart
+++ b/packages/flutter_tools/lib/src/run_cold.dart
@@ -60,7 +60,7 @@
       }
     }
 
-    for (FlutterDevice device in flutterDevices) {
+    for (final FlutterDevice device in flutterDevices) {
       final int result = await device.runCold(
         coldRunner: this,
         route: route,
@@ -90,7 +90,7 @@
 
     globals.printTrace('Application running.');
 
-    for (FlutterDevice device in flutterDevices) {
+    for (final FlutterDevice device in flutterDevices) {
       if (device.vmService == null) {
         continue;
       }
@@ -142,12 +142,12 @@
       }
       return 2;
     }
-    for (FlutterDevice device in flutterDevices) {
+    for (final FlutterDevice device in flutterDevices) {
       device.initLogReader();
     }
     await refreshViews();
-    for (FlutterDevice device in flutterDevices) {
-      for (FlutterView view in device.views) {
+    for (final FlutterDevice device in flutterDevices) {
+      for (final FlutterView view in device.views) {
         globals.printTrace('Connected to $view.');
       }
     }
@@ -170,7 +170,7 @@
 
   @override
   Future<void> cleanupAtFinish() async {
-    for (FlutterDevice flutterDevice in flutterDevices) {
+    for (final FlutterDevice flutterDevice in flutterDevices) {
       await flutterDevice.device.dispose();
     }
 
@@ -181,7 +181,7 @@
   void printHelp({ @required bool details }) {
     bool haveDetails = false;
     bool haveAnything = false;
-    for (FlutterDevice device in flutterDevices) {
+    for (final FlutterDevice device in flutterDevices) {
       final String dname = device.device.name;
       if (device.vmService != null) {
         globals.printStatus('An Observatory debugger and profiler on $dname is '
@@ -209,7 +209,7 @@
 
   @override
   Future<void> preExit() async {
-    for (FlutterDevice device in flutterDevices) {
+    for (final FlutterDevice device in flutterDevices) {
       // If we're running in release mode, stop the app using the device logic.
       if (device.vmService == null) {
         await device.device.stopApp(device.package);