Moves an incorrectly marked negative test

The following test had been marked as negative by mistake. This commits
moves it back to the positive test file.

tempest.api.compute.images.test_images:ImagesNegativeTestJSON.test_create_image_from_stopped_server

Change-Id: I61dc6fbdf269e69e76edbf5d393da64d48bb1d5e
2 files changed