Integration test insecure registry

The integrations tests use their own registry so avoid hitting docker
hub rate limits.

This was using a self signed certificate but instead use
`--insecure-registry` to let the docker daemon use HTTP.

test/integration/docker/registry/boot.sh

@@ -1,5 +1,3 @@
 #!/bin/sh
 
-while [ ! -f /certs/domain.crt ]; do sleep 1; done
-
 exec /entrypoint.sh /etc/docker/registry/config.yml