Bug 1474393 - Ensure test-verify knows when it is running in gpu mode; r=jmaher

An inconsistency in configuration between Android and desktop was causing
some tests not to be verified on Android.

testing/mozharness/mozharness/mozilla/testing/per_test_base.py

@@ -205,7 +205,7 @@ class SingleTestMixin(object):
 
         if self.config.get('per_test_category') == "web-platform":
             self._find_wpt_tests(dirs, changed_files)
-        elif self.config.get('gpu_required', 'False') != 'False':
+        elif self.config.get('gpu_required', False) is not False:
             self._find_misc_tests(dirs, changed_files, gpu=True)
         else:
             self._find_misc_tests(dirs, changed_files)

testing/mozharness/scripts/desktop_unittest.py

@@ -171,7 +171,7 @@ class DesktopUnittest(TestingMixin, MercurialScript, MozbaseMixin,
         [["--gpu-required"], {
             "action": "store_true",
             "dest": "gpu_required",
-            "default": "False",
+            "default": False,
             "help": "Run additional verification on modified tests using gpu instances."}
          ],
     ] + copy.deepcopy(testing_config_options) + \