Remove usage of locals() for formatting from cinder.tests.*

Using of locals() for formatting string is a nasty thing because:
1) It is not so clear as using explicit dicts
2) It could produce hidden errors during refactoring
3) Changing name of variable causes change in message
4) Creating a lot of unused variables

Fix bug 1171936

Change-Id: I67aa5bff650b55484ca76adf5be8555f72a4c426
Merge "Remove usage of locals() for formatting from cinder.tests.*"