Refactoring and a few small fixes
Refactoring and a few small fixes

- Use const for runtimeClassName
- Ensure the pod's RuntimeClassName is not nil before checking its value
- Use RunVMIAndExpectLaunch() to simplify test
- More small changes

Signed-off-by: Itamar Holder <b6ebf050aad0538d1e30c557853a5c8924b66230@redhat.com>

kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt