Migrate to OSTC for container images in Oniro EF repository

EF GitLab doesn't support container images. See eclipsefdn/helpdesk#1108 (closed). On the other hand, our build jobs use custom images that we store in the booting GitLab instance. Because booting is probably going to get deprecated, we want the image registry to be migrated to the OSTC instance and the corresponding CI jobs in EF infrastructure to use that registry.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information