After this patch [1], Magnum is no longer the "Container Service", it
became the "Container Infrastructure Management Service". This commit
updates the service name and description accordingly:
* Change service name from "container" to "container-infra"
* Update service description to reflect its mission
[1] https://review.openstack.org/#/c/311476/
Depends-On: I55205ff2b304678d2b53bbd4d66403078c6baac8
Closes-Bug: #1584251
Change-Id: I5c271bf3fc4d6ccecaf2918aca28ce946bcc6b22