Cleaning up CI code be removing overrides (#251)

.jenkins/precheckin.groovy

@@ -56,10 +56,9 @@ ci: {
                         "rocm-docker":[]]
     propertyList = auxiliary.appendPropertyList(propertyList)
 
-    def jobNameList = ["compute-rocm-dkms-no-npi":([ubuntu16:['rccl906']]), 
-                       "rocm-docker":([ubuntu16:['rccl906']])]
+    def jobNameList = ["compute-rocm-dkms-no-npi-hipclang":([ubuntu18:['4gfx906']])]
+    
     jobNameList = auxiliary.appendJobNameList(jobNameList)
-    jobNameList['compute-rocm-dkms-no-npi-hipclang'] = [ubuntu16:['rccl906']]
     
     propertyList.each 
     {