Description of problem (please be detailed as possible and provide log
snippets):

PVC creation using RBD storageclass where encryption is enabled using KMS fails with the following error:

E0128 05:54:51.218498       1 utils.go:136] ID: 1028 Req-ID: pvc-e3fbd0d1-e1c3-47ac-a852-1b9b73bde32e GRPC error: rpc error: code = InvalidArgument desc = invalid encryption kms configuration: "POD_NAMESPACE" is not set

The POD_NAMESPACE ENV variable is set in the csi provisioner pod:

$ oc describe pod csi-rbdplugin-provisioner-697f4498b4-rz9zl |grep POD_NAMESPACE
      POD_NAMESPACE:  openshift-storage (v1:metadata.namespace)

Version of all relevant components (if applicable):

OCS version: ocs-operator.v4.7.0-238.ci
OCP version: 4.7.0-0.nightly-2021-01-27-072811

Does this issue impact your ability to continue to work with the product
(please explain in detail what is the user impact)?
Yes, Provisioning for RBD PVC fails

Is there any workaround available to the best of your knowledge?
Not that I am aware of

Rate from 1 - 5 the complexity of the scenario you performed that caused this
bug (1 - very simple, 5 - very complex)?
2

Can this issue reproducible?
Yes

Can this issue reproduce from the UI?
Yes

If this is a regression, please provide more details to justify this:


Steps to Reproduce:
1. Create an RBD storageclass with encryption enabled
2. Create a secret containing the token from vault
3. Create an RBD PVC using the storageclass in step 1

Actual results:
The PVC is stuck in Pending state with the error 

E0128 05:54:51.218498       1 utils.go:136] ID: 1028 Req-ID: pvc-e3fbd0d1-e1c3-47ac-a852-1b9b73bde32e GRPC error: rpc error: code = InvalidArgument desc = invalid encryption kms configuration: "POD_NAMESPACE" is not set

Expected results:
PVC should be in bound state