Keep stable names for the variants that are currently built in the
Fedora infrastructure.
We can remove those once we have landed the rename in this repo and the
rename in the pungi-fedora config.
- Rename common manifests to remove fedora prefix & ostree mention
- Directly include the common manifest in each variant manifest to
reduces the number of level of indirection for the manifests
Repos are overwritten by Pungi during composes in the Fedora infra and
Pungi currently only overwrites the leaf manifest.
See: https://pagure.io/releng/issue/11969
Reverts: 49db8be manifests: Move repos config to common manifest
