Revert "Run coverage tests verbosely to help diagnose timeouts. (#8198)" (#8204)

This reverts commit fac9efba.

The timeout was fixed by 6795c4ab.

dev/bots/test.dart

@@ -56,10 +56,8 @@ Future<Null> main() async {
   );
 
   List<String> coverageFlags = <String>[];
-  if (Platform.environment['TRAVIS'] != null && Platform.environment['TRAVIS_PULL_REQUEST'] == 'false') {
+  if (Platform.environment['TRAVIS'] != null && Platform.environment['TRAVIS_PULL_REQUEST'] == 'false')
     coverageFlags.add('--coverage');
-    coverageFlags.add('-v');
-  }
 
   // Run tests.
   await _runFlutterTest(p.join(flutterRoot, 'packages', 'flutter'),