Revert client.copy_file to use util.CMD
Revert client.copy_file to use util.CMD

The command will get too long when we encode it.

Signed-off-by: Micu Matei-Marius <ffdce18e3aed9c8a40562979086663cc29b060a9@cloudbasesolutions.com>

micumatei/cloudbase-init-ci,stefan-caraiman/cloudbase-init-ci,cloudbase/cloudbase-init-ci