Docker is using 172.17.0.0/16 by default for bridge networking on
docker0, and this might cause routing problems for operator networks.

This change introduces docker_disable_default_network to disable the
bridge networking by putting "bridge: none"[1] to daemon.json

Bridge networking does not work without iptables, so we set the default
for docker_disable_default_network to
docker_disable_default_iptables_rules.

For better defaults, this feature will be enabled by default in
Wallaby.

[1] https://docs.docker.com/engine/reference/commandline/dockerd/

Change-Id: Ic745300b27e50132d80d03787fa4abfada2d0173
Closes-Bug: #1848249
Related-Bug: #1849275