Re-enable the `test_restrict` unit-test
Re-enable the `test_restrict` unit-test

This test currently fails.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@citrix.com>

mirage/ocaml-xenstore-server,mirage/ocaml-xenstore-server,djs55/ocaml-xenstore-server