Fix button.confirm not displaying anything if it has no confirm conte…

…nt (#7474)

# About the pull request

This PR is a follow-up to #5777 and #6244 because Button.Confirm was
changed how its confirm content was displayed. It used to display the
children always, but TG since changed it to display either the confirm
content or the children. Now the children will be displayed if there is
no confirm content set.

# Explain why it's good for the game

Fixes confusing buttons in the ping relay browser.

# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Before:

![image](https://github.com/user-attachments/assets/a48b01e9-ca8d-4521-9ac5-8f4cfb07f6eb)

After:

![image](https://github.com/user-attachments/assets/46151d2f-139c-4f30-b4fb-0892572bf64f)

</details>

# Changelog
:cl: Drathek
ui: Fixed the ping relay buttons not displaying anything when clicked on
the first time. Now Button.Confirm.confirmContent will only replace
children if it is truthy.
/:cl:

tgui/packages/tgui/components/Button.tsx

@@ -256,7 +256,7 @@ const ButtonConfirm = (props: ConfirmProps) => {
       }}
       {...rest}
     >
-      {clickedOnce ? confirmContent : children}
+      {clickedOnce && confirmContent ? confirmContent : children}
     </Button>
   );
 };