[tool] Build all_packages command against Flutter Android SDK version to match example apps

Author: jmagman

script/tool/lib/src/create_all_packages_app_command.dart

@@ -243,9 +243,9 @@ dependencies {}
       gradleFile,
       replacements: <String, List<String>>{
         if (gradleFileIsKotlin)
-          'compileSdk': <String>['compileSdk = 34']
+          'compileSdk': <String>['compileSdk = flutter.compileSdkVersion']
         else ...<String, List<String>>{
-          'compileSdkVersion': <String>['compileSdk 34'],
+          'compileSdkVersion': <String>['compileSdk flutter.compileSdkVersion'],
         }
       },
       regexReplacements: <RegExp, List<String>>{

script/tool/test/create_all_packages_app_command_test.dart

@@ -342,7 +342,7 @@ android {
           buildGradle,
           containsAll(<Matcher>[
             contains('This is the legacy file'),
-            contains('compileSdk 34'),
+            contains('compileSdk flutter.compileSdkVersion'),
           ]));
     });
 
@@ -375,7 +375,7 @@ android {
       expect(
           buildGradle,
           containsAll(<Matcher>[
-            contains('compileSdk 34'),
+            contains('compileSdk flutter.compileSdkVersion'),
             contains('androidx.lifecycle:lifecycle-runtime'),
           ]));
     });