Use the ostree-push 1.x protocol on the default server

To handle the incompatibility between the ostree-push 0.x and 1.x protocols a separate server for the 1.x protocol was set up on port 2222 and we started using it since the commit f9e8b494 "Add support for ostree-push 1.0".

Multi-protocol compatibility has been introduced into our version of ostree-push, so we can use the main port 22 for the 1.x protocol as well.