fix(quickstart): Fix dark mode issue when skipping step (#80905)

### Before
![CleanShot 2024-11-18 at 17 31
31](https://github.com/user-attachments/assets/dc04c6f7-acc0-42c9-bbb9-25c99bb5ee9f)
### After
![CleanShot 2024-11-18 at 17 32
26](https://github.com/user-attachments/assets/e5e0b13b-57d2-44fa-96ac-f29d4e780307)

Author: matejminar

static/app/components/onboardingWizard/skipConfirm.tsx

@@ -87,7 +87,7 @@ const Confirmation = styled(({onDismiss, onSkip, visible: _, ...props}: ConfirmP
   align-items: center;
   flex-direction: column;
   justify-content: center;
-  background: rgba(255, 255, 255, 0.9);
+  background: ${p => p.theme.surface200};
   animation: ${fadeIn} 200ms normal forwards;
   font-size: ${p => p.theme.fontSizeMedium};