Remove link to el7toel8 repository

Linking a repository is needed, when the current
repository requires things like Tags, Models, Topics, Workflows
etc from another repository which does not seem to be the case in
our situation.

With this link leapp always expects el7toel8 to be available
which is not the case for cloudlinux 8.

Author: Monstrofil

repos/system_upgrade/cloudlinux/.leapp/info

@@ -1 +1 @@
-{"name": "cloudlinux", "id": "427ddd90-9b5e-4400-b21e-73d77791f175", "repos": ["644900a5-c347-43a3-bfab-f448f46d9647", "c47fbc3d-ae38-416e-9176-7163d67d94f6", "efcf9016-f2d1-4609-9329-a298e6587b3c"]}
+{"name": "cloudlinux", "id": "427ddd90-9b5e-4400-b21e-73d77791f175", "repos": ["644900a5-c347-43a3-bfab-f448f46d9647", "efcf9016-f2d1-4609-9329-a298e6587b3c"]}