packagers: miniyum: we only need system_r

rpm_t type is added automatically by the rpm_execcon(),
question is why the system_r is not added...
the rpm_t conflict with other tasks install should do
such as interactive with dbus.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=904153
Change-Id: Iebc0c3fb20c5720a5e05ba0cfda8931ab80a152a
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>