test(stage): add test to cover scenario when clouddriver returns a failure

[edgarulg]

Adding a missing test for WaitForManifestStableTask. This test validates that the task's context is reset if Clouddriver returns a SpinnakerServerException while waiting for the manifests to stabilize. This means that the stable manifests previously validated by Orca are removed from the context, and Orca restarts the validation process for all deployed manifests.

[edgarulg]

@dbyron-sf I removed the AssertionsForClassTypes import and commit your suggested changes. Thanks for the feedback.

[edgarulg]

@dbyron-sf I removed the star imports you asked me to remove. FYI