packaging: engine-service: remove /usr/bin symlink

The engine-service script is not a utility to be used by user but by
downstream packager, hence no reason to install at /usr/bin.

Change-Id: I49fc25ad586b8f04e1588d04ab772858f2bfd169
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>