fix(kubernetes): pin pending PVC consumers

[MarcStdt]

Summary

• treat scheduled Pending runtime Pods as active RWO PVC consumers
• co-locate concurrent persistent commands with coldstarter init Pods
• cover the Pending consumer case

Validation

• GOCACHE=/tmp/druid-go-cache go test ./internal/runtime/kubernetes
• reproduced production Multi-Attach with Minecraft coldstarter on prod-3 and Developer Mode on prod-5

[druid-infra]

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