Improved heal02 test to create a flavor with random name

Change-Id: I68d54314528bf7cf08227759e37b85b355319226
Signed-off-by: aguilard <e.dah.tid@telefonica.com>

robot-systest/testsuite/heal_02-scale_vdu_healing.robot

@@ -49,7 +49,7 @@ ${nsd_pkg}   volumes_nativecharm_ns
 ${nsd_name}   volumes_nativecharm-ns
 
 # NS instance name and configuration
-${flavor_name}   osm.heal_02
+${flavor_name_prefix}   osm.heal02
 ${ns_name}   heal_02
 ${ns_timeout}   6min
 ${scale_wait_time}   4min
@@ -77,7 +77,8 @@ Create NS Descriptor
 
 
 Create Test Flavor
-    Delete Flavor   ${flavor_name}
+    ${rand}=   Generate Random String   6   [NUMBERS]
+    ${flavor_name}=   Catenate   SEPARATOR=_   ${flavor_name_prefix}   ${rand}
     ${id}=   Create Flavor   ${flavor_name}   1   1024   10
     Set Suite Variable   ${flavor_id}   ${id}