No error reported when a none-existing diagnosis shall be removed with PNS_IF_REMOVE_DIAG_REQ

If the service PNS_IF_REMOVE_DIAG_REQ is used with a diagnosis handle that was never given back by protocol stack (or the handle was used to remove a diagnosis some time before) the confirmation does not report an error.

It is expected that the confirmation reports an error indicating the wrong handle to the user.