fix(influxdb-seed): swap emptyDir for ceph-block ephemeral PVC

emptyDir backs onto node ephemeral-storage. With only ~4.5 GiB free per
node, the 10.5 GiB download triggered kubelet eviction (Reason: Evicted,
Exit 137) long before the file finished.

Generic ephemeral volume claims a 20 GiB RWO PVC on ceph-block for the
pod's lifetime — Ceph-backed, auto-deleted with the pod, and won't
compete with node-level ephemeral pressure.

Bump Job v5 → v6.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

kubernetes/apps/influxdb-seed/seed-job.yaml

@@ -18,7 +18,7 @@
 apiVersion: batch/v1
 kind: Job
 metadata:
-  name: influxdb-data-seed-v5
+  name: influxdb-data-seed-v6
   namespace: influxdb
 spec:
   ttlSecondsAfterFinished: 3600
@@ -27,9 +27,19 @@ spec:
     spec:
       restartPolicy: Never
       volumes:
+        # Generic ephemeral PVC on ceph-block. emptyDir would count against
+        # node ephemeral-storage (~4.5 GiB free per node → instant eviction
+        # for a 10 GiB file). The PVC is created with the pod and deleted
+        # when the pod terminates.
         - name: scratch
-          emptyDir:
-            sizeLimit: 15Gi
+          ephemeral:
+            volumeClaimTemplate:
+              spec:
+                accessModes: ["ReadWriteOnce"]
+                storageClassName: ceph-block
+                resources:
+                  requests:
+                    storage: 20Gi
       containers:
         - name: seed
           image: influxdb:2.7.4