Remove unused/redundant methods in cinder/test.py

The following methods are not used anywhere in Cinder
- assertDictListMatch()
- assertSubDictMatch()

The following methods are implemented in testtools
- assertIn()
- assertNotIn()

Change-Id: Iea96f7761c33ac774b5b4ae71e544aa007ba1bb2
Merge "Remove unused/redundant methods in cinder/test.py"