Add new unit test(s) to argo-rollouts-manager to verify 'rollouts-plugin-trafficrouter-openshift' ConfigMap is created correctly

[jgwest]

This PR was contributed, which adds code that reconciles the Argo Rollouts ConfigMap settings resource, in order to contribute the OpenShift Routes traffic.

However, there were not Reconcile unit tests contributed as part of that PR. We should add those as part of this issue.

Issue Criteria:

• Write new Ginkgo-based unit tests that verify that the ConfigMap created by #15 works as expected.
  • Brainstorm and contribute any additional unit tests we need for this code.
• You will likely need to contribute a fix to #22 as part of this as well.

[jgwest]

Red Hat issue tracker: https://issues.redhat.com/browse/GITOPS-3910