Switch studio-client and overview to CoreMedia vendored unprivileged nginx image.

The Docker images for studio-client and overview now use the CoreMedia vendored nginx unprivileged image. Port configuration and other adjustments have been applied to support the unprivileged setup. As a result, these containers no longer use port 80 and have been reconfigured to use port 8080. This change may require adjustments to your existing deployment or firewall settings."

(CMS-16467)