packaging: modify enigne.conf.d setup files prefix

previously we used '50-' prefix, however there is no reason for setup
default to be loaded so late in change, so now it was modified to
'10-' prefix.

clean all configuration files when engine-clean is executed to avoid
leftovers.

Change-Id: I173faede1f39b87a14ede05c04e0ab4da7e8e5d3
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>