[FIX] test_new_api: properly conclude tours

- the x2many tour would finish on a click canceling the creation but
  not wait for that to resolve, leading to the driver catching it in
  the act (checking before the client had had the time to switch),
  just need to wait for the list view to be displayed
- the constraints tour would just drop in the middle of a creation
  with an error dialog open, so need to finish the entire thing and go
  back to the list view

Part-of: odoo/odoo#96517

odoo/addons/test_new_api/static/tests/tours/constraint.js

@@ -27,6 +27,11 @@ odoo.define('web.test.constraint', function (require) {
     }, { // check popup content
         content: "check notification box",
         trigger: '.o_dialog_warning:contains(The color code must be positive !)',
-        run: function () {}, // it's a check
-    }]);
+        run() {}
+    }, {
+        content: "close notification box",
+        trigger: '.modal-footer .o-default-button',
+    },
+    ...tour.stepUtils.discardForm(),
+    ]);
 });

odoo/addons/test_new_api/static/tests/tours/x2many.js

@@ -472,13 +472,11 @@ odoo.define('web.test.x2many', function (require) {
         trigger: '.o_field_widget[name=name] input',
         run:     'text {generate_dummy_message}',
     }, {
-        content: "chuck update and new dummy message happened",
+        content: "check update and new dummy message happened",
         trigger: '.o_field_widget[name=messages] .o_data_row .o_list_number:containsExact(22)',
         extra_trigger: '.o_field_widget[name=important_messages] .o_data_row .o_list_number:containsExact(22)',
         run: function () {}, // it's a check
-    }, { // cancel
-        content: "cancel change",
-        trigger: '.o_cp_buttons .o_form_button_cancel',
-        run: 'click',
-    }]);
+    },
+    ...tour.stepUtils.discardForm(),
+    ]);
 });