web: change node registration parameter order (#2607)

This change makes editing the generated command easier.
For example, after pasting into a terminal, the cursor position will be
near the username portion which requires editing.

hscontrol/templates/register_web.go

@@ -28,7 +28,7 @@ func RegisterWeb(registrationID types.RegistrationID) *elem.Element {
 			elem.H2(nil, elem.Text("Machine registration")),
 			elem.P(nil, elem.Text("Run the command below in the headscale server to add this machine to your network: ")),
 			elem.Code(attrs.Props{attrs.Style: codeStyleRegisterWebAPI.ToInline()},
-				elem.Text(fmt.Sprintf("headscale nodes register --user USERNAME --key %s", registrationID.String())),
+				elem.Text(fmt.Sprintf("headscale nodes register --key %s --user USERNAME", registrationID.String())),
 			),
 		),
 	)

integration/scenario.go

@@ -842,6 +842,7 @@ func (s *Scenario) runHeadscaleRegister(userStr string, body string) error {
 		return errParseAuthPage
 	}
 	key := keySep[1]
+	key = strings.SplitN(key, " ", 2)[0]
 	log.Printf("registering node %s", key)
 
 	if headscale, err := s.Headscale(); err == nil {