Correctly set mirrors for Rocky host image builds

Author: MoteHue

etc/kayobe/stackhpc-overcloud-dib.yml

@@ -58,8 +58,8 @@ stackhpc_overcloud_dib_env_vars_default:
 
 stackhpc_overcloud_dib_env_vars_ark:
   DIB_CONTAINERFILE_BUILDOPTS: >-
-    --build-arg=ROCKY_USE_MIRRORS=true
-    --build-arg=ROCKY_MIRROR_URLS={{ [stackhpc_repo_rocky_9_baseos_url, stackhpc_repo_rocky_9_appstream_url] | join(',') }}
+    --build-arg=ROCKY_USE_CUSTOM_DNF_MIRRORS=true
+    --build-arg=ROCKY_CUSTOM_DNF_MIRROR_URLS={{ [stackhpc_repo_rocky_9_baseos_url, stackhpc_repo_rocky_9_appstream_url] | join(',') }}
   DIB_DISTRIBUTION_MIRROR: "{{ stackhpc_repo_ubuntu_noble_url if os_distribution == 'ubuntu' else '' }}"
 
 # StackHPC overcloud DIB image packages.