Mock time.sleep for test_lv_deactivate_timeout test

Test local_dev.test_brick_lvm.BrickLvmTestCase.test_lv_deactivate_timeout
doesn't mock time.sleep which is used for retries.

It increases test execution time to ~2s instead of ~0.02.

Change-Id: Id3704d90de0b3d04401c0b7b7686470685dbc1cc
Closes-Bug: #1620986

os_brick/tests/local_dev/test_brick_lvm.py

@@ -373,7 +373,8 @@ class BrickLvmTestCase(base.TestCase):
             self.vg.create_volume('test', '1G')
             self.vg.deactivate_lv('test')
 
-    def test_lv_deactivate_timeout(self):
+    @mock.patch('time.sleep')
+    def test_lv_deactivate_timeout(self, mock_sleep):
         with mock.patch.object(self.vg, '_execute'):
             is_active_mock = mock.Mock()
             is_active_mock.return_value = True