osdc/hf-cache: enable on staging clusters

Add hf-cache to the modules list for meta-staging-aws-uw1 and
meta-staging-aws-ue1 (after arc-runners) so it actually deploys there:
the per-cluster bucket + IRSA, the read-only rclone mount DaemonSet, and the
BEGIN_HF_CACHE block in the runner job-pod template. Prod and lf-* clusters are
untouched. Deploy: just deploy-module <staging> hf-cache && ... arc-runners.

ghstack-source-id: ceced5c
Pull-Request: #825

Author: huydhn

osdc/clusters.yaml

@@ -181,6 +181,7 @@ clusters:
       - arc
       - nodepools
       - arc-runners
+      - hf-cache
       - keda
       - buildkit
       - zombie-cleanup
@@ -254,6 +255,7 @@ clusters:
       - arc
       - nodepools
       - arc-runners
+      - hf-cache
       - keda
       - buildkit
       - zombie-cleanup