Removes font override in favour of Storybook parameter (#39988)

app/javascript/mastodon/components/_theme_playground/theme_playground.module.scss

@@ -1,10 +1,6 @@
 @use '@/styles/mastodon/mixins';
 
 .wrapper {
-  // Override global body font variable because Storybook
-  // doesn't have the `data-redesign` html attribute
-  --font-body: Inter, sans-serif;
-
   position: relative;
   display: grid;
   grid-template-columns: 250px 1fr;

app/javascript/mastodon/components/_theme_playground/theme_playground.stories.tsx

@@ -7,6 +7,7 @@ const meta = {
   component: ThemePlayground,
   parameters: {
     layout: 'fullscreen',
+    redesign: true,
   },
 } satisfies Meta<typeof ThemePlayground>;