fuel-plugin: Remove use of plugin-defined role

fuel-plugin: Remove use of plugin-defined role

The use of a fuel plugin-defined role not working since rebase
to Fuel8 so work around this by removing dependecy on this feature
for imminent Rel/B.

Change-Id: Icd1ee1c8f05a1c26e8da7f80d2d7206374099a93
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Michal Skalski <mskalski@mirantis.com>
Reviewed-by: Jonas Bjurel <jonas.bjurel@ericsson.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Mark D. Gray <mark.d.gray@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Brian Castelli <brian.castelli@spirent.com>
(cherry picked from commit 4064fc0e839c26c38a38ee71e63673ed59d8547b)