Remove flutter attach test timeout (#53317)

dev/devicelab/bin/tasks/flutter_attach_test_android.dart

@@ -57,11 +57,7 @@ Future<void> testReload(Process process, { Future<void> Function() onListening }
   }
 
   await eventOrExit(listening.future);
-  await eventOrExit(ready.future).timeout(const Duration(seconds: 15), onTimeout: () {
-    // If it can't attach in 15 seconds, it's not capable of finding the
-    // observatory URL in the logs.
-    throw TaskResult.failure('Failed to attach to running Flutter process');
-  });
+  await eventOrExit(ready.future);
 
   if (exitCode != null)
     throw TaskResult.failure('Failed to attach to test app; command unexpected exited, with exit code $exitCode.');

dev/devicelab/manifest.yaml

@@ -373,6 +373,7 @@ tasks:
       Tests the `flutter attach` command.
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
+    timeout_in_minutes: 20
 
   named_isolates_test:
     description: >