CP-311613: do not attempt to export delta VHD from SMAPIv3

VHD export takes various shortcuts, and delta export only works if the source is also VHD.
Otherwise it fails with:
`Failure("Cannot compute differences on non-VHD images")`

If the source is already qcow2, like for SMAPIv3, then this is not (yet)
expected to work, so skip those tests on SMAPIv3 for now.

Note that regular export works, it is just the delta export that fails (specifying `base=`
in `xe vdi-export`).

Signed-off-by: Edwin Török <edwin.torok@citrix.com>
(cherry picked from commit 8ac4476)

Author: edwintorok

ocaml/quicktest/quicktest_vdi_ops_data_integrity.ml

@@ -256,9 +256,9 @@ let large_data_integrity_tests vdi_op op_name =
 let sr_with_vdi_create_destroy =
   Qt_filter.SR.(all |> allowed_operations [`vdi_create; `vdi_destroy] |> not_iso)
 
-let supported_srs test_case =
+let supported_srs ?(f = Fun.id) test_case =
   let open Qt_filter in
-  test_case |> conn |> sr sr_with_vdi_create_destroy
+  test_case |> conn |> sr (f sr_with_vdi_create_destroy)
 
 (* XXX Currently only GFS2 SRs support sparse reading of VDIs exported as TAR *)
 let supported_gfs2_srs test_case =
@@ -276,7 +276,7 @@ let tests () =
     )
   @ (delta_data_integrity_tests delta_export_import_vhd
        "VDI delta export/import to/from VHD file"
-    |> supported_srs
+    |> supported_srs ~f:Qt_filter.SR.smapiv1
     )
   @ (data_integrity_tests export_import_tar "VDI export/import to/from TAR file"
     |> supported_srs