Replace custom patching in `setUp` on HypervisorsSampleJsonTests

It would be better if we get rid of `setUp` method in 
`HypervisorsSampleJsonTests` in which happens 
patching and replace it on class-mock.

Change-Id: If3758564c4febf2019ecdb4fce972580a562f759
Merge "Replace custom patching in `setUp` on HypervisorsSampleJsonTests"