Update generate_gradle_lockfiles.dart to handle batch updating kotlin Gradle files (#162628)

Also removes the only entry from the exclusion script, as this fixes the
reason for its exclusion.

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---------

Co-authored-by: Gray Mackall <mackall@google.com>

examples/hello_world/android/build.gradle.kts

@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Contents of this file should be generated automatically by
-// dev/tools/bin/generate_gradle_lockfiles.dart, but currently are not.
-// See #141540.
+// This file is auto generated.
+// To update all the settings.gradle files in the Flutter repo,
+// See dev/tools/bin/generate_gradle_lockfiles.dart.
 
 allprojects {
     repositories {

examples/hello_world/android/settings.gradle.kts

@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Contents of this file should be generated automatically by
-// dev/tools/bin/generate_gradle_lockfiles.dart, but currently are not.
-// See #141540.
+// This file is auto generated.
+// To update all the settings.gradle files in the Flutter repo,
+// See dev/tools/bin/generate_gradle_lockfiles.dart.
 
 pluginManagement {
     val flutterSdkPath =