replace assertTrue(isinstance) to assertIsInstance

some of tests use different method of assertTrue(isinstance(A, B))
or assertEqual(type(A), B). The correct way is to use
assertIsInstance(A, B) provided by testtools

Change-Id: Idd931d27b13a46800e27393a98da096d41442320
Closes-bug: #1268480
Merge "replace assertTrue(isinstance) to assertIsInstance"