Change "Starting Xcode build" text to "Running xcode build" (#27181)

This status shows for the duration of the run, not just while starting. It looks kinda weird in the editors to show a progress bar for "Starting Xcode build" and then removing it once it completes.

packages/flutter_tools/lib/src/ios/mac.dart

@@ -486,7 +486,7 @@ Future<XcodeBuildResult> buildXcodeProject({
   }
 
   final Stopwatch buildStopwatch = Stopwatch()..start();
-  initialBuildStatus = logger.startProgress('Starting Xcode build...', timeout: kFastOperation);
+  initialBuildStatus = logger.startProgress('Running Xcode build...', timeout: kFastOperation);
   final RunResult buildResult = await runAsync(
     buildCommands,
     workingDirectory: app.project.hostAppRoot.path,