[input] [drac] Don't define duplicate 'architecture:' key (see bug 12427)

input/grid5000/sites/grenoble/clusters/drac/drac.yaml

@@ -11,10 +11,6 @@ nodes:
     processor:
       microarchitecture: POWER8NVL
       clock_speed: 4000000000
-    architecture:
-      nb_cores: 20
-      nb_procs: 2
-      nb_threads: 160
     supported_job_types:
       deploy: true
       besteffort: true