Remove ORA1 role from devstack, in preparation for deprecation

[ORA-696](https://openedx.atlassian.net/browse/ORA-696): Update DevStack to not have ORA1 by default

This PR removes ORA1 from the devstack base image.  It does NOT remove it from the sandbox, vagrant-fullstack, or the release version of devstack (which assumes ORA1 folder sharing).

@feanil Please review.  When the next configuration release goes out, someone will need to update `vagrant/release/devstack/Vagrantfile` as well.