Use a separate config_volume for swift_ringbuilder puppet_config tasks.
This is necessary so that the swift_ringbuilder and swift-storage
services don't both rsync files to the same bind mounted directory.
The rsync command from docker-puppet.py uses --delete-after, so when
they both use the same config_volume, they can end up deleting the files
generated by the other (depending on the order of execution).
Even though a separate config_volume is used, the rings must still end up
in /etc/swift for the swift services containers. An additional
container init task is used to copy the ring files into
/var/lib/config-data/puppet-generated/swift/etc/swift so that they will
be present when the actual swift services containers are started.
Change-Id: I05821e76191f64212704ca8e3b7428cda6b3a4b7
Closes-Bug: #1710952
cba00abb75