remove update-downstream-server-version job

Before we can finalize https://gitlab.com/gitlab-org/release-tools/issues/384 the update-downstream-server-version has to be removed.

A first iteration could be that we move it to a manual job for the first milestone.

Edited Feb 06, 2020 by Alessio Caiazza

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