Allow KubernetesMockServer in TestConfiguration be created without https

[lumeche]

I had some problems with my test related to security and because of that I wanted to ue the KubernetesMockServer started in non secure mode. Unfortunatelly this is not configurable in the TestConfiguration class.
What I want to propose is to make this configurable through the class TestConfigurationProperties.

I can offer a PR if you consider this acceptable