[flutter_tool] Remove the synchronous -showBuildSettings (#40435)

diff --git a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
index 6828bca..163f848 100644
--- a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
+++ b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
@@ -173,7 +173,7 @@
 
     testUsingContext('creates swift Podfile if swift', () async {
       when(mockXcodeProjectInterpreter.isInstalled).thenReturn(true);
-      when(mockXcodeProjectInterpreter.getBuildSettingsAsync(any, any))
+      when(mockXcodeProjectInterpreter.getBuildSettings(any, any))
           .thenAnswer((_) async => <String, String>{
         'SWIFT_VERSION': '4.0',
       });