use current fatimage for doca test build

Author: sjpb

.github/workflows/doca.yml

@@ -36,10 +36,10 @@ jobs:
       matrix: # build RL8, RL9
         build:
           - image_name: openhpc-doca-RL8
-            source_image_name: openhpc-RL8 # TODO: needs to be injected from environments/.stackhpc/terraform/cluster_image.auto.tfvars.json
+            source_image_name: "${{ fromJSON(env.FAT_IMAGES).cluster_image.RL8 }}"
             inventory_groups: doca
           - image_name: openhpc-doca-RL9
-            source_image_name: openhpc-RL9 # TODO: as above
+            source_image_name: "${{ fromJSON(env.FAT_IMAGES).cluster_image.RL9 }}"
             inventory_groups: doca
     env:
       ANSIBLE_FORCE_COLOR: True