Simplify late payment warning text

- Change 'Late payments after X minutes are kept' to 'Late payments are kept'
- Removes dynamic time calculation and makes message clearer

make_post_sell/templates/crypto_checkout.j2

@@ -503,7 +503,7 @@
     <ul style="margin: 10px 0;">
       <li>Underpayments are kept</li>
       <li>Overpayments are kept</li>
-      <li>Late payments after <strong>{{ ((expires_at - now) // 60000) if expires_at and (expires_at - now) > 0 else 'expiry' }} minutes</strong> are kept</li>
+      <li>Late payments are kept</li>
       <li><strong>Out of stock:</strong> Funds transferred to shop (no refund possible)</li>
       <li>Wrong address payments cannot be recovered</li>
     </ul>