Use process.kill instead of process manager killPid

Author: gspencergoog

pkgs/dart_mcp_server/lib/src/mixins/flutter_launcher.dart

@@ -227,7 +227,7 @@ base mixin FlutterLauncherSupport
     } catch (e, s) {
       log(LoggingLevel.error, 'Error launching Flutter application: $e\n$s');
       if (process != null) {
-        processManager.killPid(process.pid);
+        process.kill();
         // The exitCode handler will perform the rest of the cleanup.
       }
       return CallToolResult(

pkgs/dart_mcp_server/test/tools/flutter_launcher_test.dart

@@ -460,7 +460,6 @@ void main() {
             'TimeoutException',
           ]),
         );
-        test.expect(mockProcessManager.killedPids, [processPid]);
 
         server.shutdown();
         client.shutdown();