xapi_vm_clone: Remove impossible, confusing case when dealing with suspend VDIs (#6704)

This case was impossible due to 2 reasons:
1. the polymorphic variant `Runnning used had a typo
2. the reference for the suspend VDI is only present when the VM is
suspended, and otherwise is Ref.null. This means that when the VM is
running, the code takes the case before this one.

I didn't see any code dealing with shared suspend images, so I'd rather
avoid making the clone and deal with the shared situation.

Author: psafont

ocaml/xapi/xapi_vm_clone.ml

@@ -507,9 +507,6 @@ let clone ?snapshot_info_record ?(ignore_vdis = []) disk_op ~__context ~vm
                 let original = Db.VM.get_suspend_VDI ~__context ~self:vm in
                 if original = Ref.null || disk_op = Disk_op_snapshot then
                   Ref.null
-                else if disk_op = Disk_op_checkpoint && power_state = `Runnning
-                then
-                  original
                 else
                   clone_single_vdi rpc session_id disk_op ~__context original
                     driver_params