OpenEBS - Upgrade to v4

[alxbl]

OpenEBS v4 is out and is a significant refactor with several deprecations, including dynamic-nfs-provisioner.

• Uninstall OpenEBS v3
• Remove dynamic-nfs-provisioner and zfs-rwx storage class
• Install OpenEBS v4 (without replicated storage for now)
• For each deployment with a zfs-rwx PVC:
  • Rename zfs-rwx backing ZFS datasets (dynamically allocated zfs-rwo PVs)
  • Manually create PV with matching name and volume.claimRef
  • Create NFS server deployment with strict netpol and PVC for renamed PV with proper claim.volumeName
    • Make a sub-chart for this?
  • Update charts with zfs-rwx PVCs to use NFS mounts to the proper storage
• Enable monitoring