Merge pull request #40000 from jsafrane/storage-ga-remove-alpha

Automatic merge from submit-queue

Remove alpha provisioning

This is the first part of https://github.com/kubernetes/features/issues/36

@kubernetes/sig-storage-misc 

**Release note**:
```release-note
Alpha version of dynamic volume provisioning is removed in this release. Annotation
"volume.alpha.kubernetes.io/storage-class" does not have any special meaning. A default storage class
and  DefaultStorageClass admission plugin can be used to preserve similar behavior of Kubernetes cluster,
see https://kubernetes.io/docs/user-guide/persistent-volumes/#class-1 for details.
```

examples/storage/cassandra/README.md

@@ -254,8 +254,6 @@ spec:
   volumeClaimTemplates:
   - metadata:
       name: cassandra-data
-      annotations:
-        volume.alpha.kubernetes.io/storage-class: anything
     spec:
       accessModes: [ "ReadWriteOnce" ]
       resources:

examples/storage/cassandra/cassandra-statefulset.yaml

@@ -77,8 +77,6 @@ spec:
   volumeClaimTemplates:
   - metadata:
       name: cassandra-data
-      annotations:
-        volume.alpha.kubernetes.io/storage-class: anything
     spec:
       accessModes: [ "ReadWriteOnce" ]
       resources: