packaging: Don't check that root runs the service

We used to check that the service script is only executed by root, but
this is already guaranteed by the systemd configuration. In addition
lifting this restriction helps to run the engine with the service script
in development environments.

Change-Id: I52d784cb5f84627a175e20e0fdc7b1f91076f478
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>