`infrared tripleo-undercloud --update-undercloud yes` failed to run `openstack tripleo container image prepare` because the subcommand doesn't exist.

[knoha-rh]

infrared tripleo-undercloud --update-undercloud yes tries to use openstack tripleo container image prepare command then it failed to run because the subcommand doesn't exist.

[knoha-rh]

I confirmed that some python-tripleoclient version doesn't support 'openstack tripleo container image prepare' command. It causes this issue. In my opinion, if infrared can't use the command, it should fall back to use 'openstack overcloud container image prepare' command.