[flutter_tools] When running tool tests locally, test failures sometimes cause the runner to hang #141823
Description
Specifically, for tests with the testUsingContext wrapper, a test failure will cause the runner to hang until it's timed out after 15 minutes. Consider this minimal test:
import '../src/common.dart';
import '../src/context.dart';
void main() {
testUsingContext('trivial test', () {
fail('failure');
});
}