Address minor FE review comments

app/assets/javascripts/pages/projects/shared/permissions/components/settings_panel.vue

@@ -172,7 +172,7 @@ export default {
     },
     showVisibilityConfirmModal: {
       type: Boolean,
-      required: true,
+      required: false,
       default: false,
     },
   },

spec/frontend/pages/projects/shared/permissions/components/settings_panel_spec.js

@@ -216,7 +216,7 @@ describe('Settings Panel', () => {
         await findProjectVisibilityLevelInput().setValue(visibilityOptions.PRIVATE);
         await findConfirmDangerButton().vm.$emit('confirm');
 
-        expect(wrapper.emitted('confirm').length).toBe(1);
+        expect(wrapper.emitted('confirm')).toHaveLength(1);
       });
     });
   });