onboarding: change button appearance (#92108)

Make buttons look unselected when the checkbox is not pressed.



https://github.com/user-attachments/assets/1a156d11-fa33-404c-84dc-3ab673c2e88a

Author: JonasBa

static/app/components/onboarding/productSelection.tsx

@@ -424,10 +424,6 @@ export function ProductSelection({
 
 const ProductButton = withChonk(
   styled(Button)`
-    border: 1px solid ${p => p.theme.purple300};
-    color: ${p => p.theme.purple300};
-    background: ${p => p.theme.purple100};
-
     :hover,
     :focus-visible {
       border: 1px solid ${p => p.theme.purple300};