Following internal discussion, the Trivy Cloud integration does not need to be so local user focussed which removes the need for a lot of the cloud config control and the login/logout functionality.

Previously, a custom config was created (trivy-cloud.yaml) - this is redundant as there is nothing too complex in there that it can't go in the existing Trivy config so the settings should be accessible through the existing config and Viper

To easily transition an existing CI pipeline, the TRIVY_CLOUD_TOKEN should just be used, rather than having to go through a login/scan flow.