Revert "Deploy the build ssh key to auth_keys"

This commits starts using the copy-build-sshkey role, however
the role is buggy, so we should first revert this, then use
reapply this after it's tested.

This reverts commit 4bdb01e60a.

Change-Id: Ibbcfd4a0a9c37ce819cd2ad14109e9cdd20b3a1e

playbooks/multinode/pre.yaml

@@ -23,8 +23,3 @@
     - peers
   roles:
     - multi-node-bridge
-
-- name: Copy the build ssh key to authorized_keys on all hosts for root
-  hosts: all
-  roles:
-    - copy-build-sshkey