Add Unit tests that check the change of values in sub-resources.

We currently have fairly good testing around creating new Solr Clouds & Prometheus Exporters. However, the unit tests do not check that values of dependent resources are correctly updated when the Spec of a cloud/exporter is changed.

**Desired Solution**
Have some tests that make sure that a cloud is set up correctly, then make sure that when values are changed, the underlying kubernetes state changes along with it.

Start by locating the existing unit tests for creating Solr Clouds and Prometheus Exporters. Add coverage that changes their Specs after setup and verifies the dependent Kubernetes state is updated accordingly; done means both resource types are checked for changed values.

Written by the indexing model from the issue text.