Add namespace to persistent volume path

[tstromberg]

Fixes #8987 - though we will also need to bump STORAGE_PROVISIONER_TAG to make it hit production.

Verified after bumping version to v3 using:

minikube docker-env | source        
make storage-provisioner-image
env TEST_ARGS="-test.run TestFunctional/parallel/PersistentVolumeClaim --profile minikube --cleanup=false" make integration

[k8s-ci-robot]

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