The storage provisioner (Longhorn) needs a few seconds to create and
attach the volume. Previously the Job was created immediately after
the PVC, and the scheduler rejected the pod with 'unbound immediate
PersistentVolumeClaims'. Now ensure_shared_volume_pvc polls until the
PVC reaches Bound status (up to 120s) before returning.
Also removes the early-exit on PodScheduled=False in wait_for_pod_running
since transient scheduling failures (like unbound PVCs) resolve on
their own and shouldn't be treated as fatal.