Made all place of Cubits/buybitcoinworldwide.com button clickable

[luixxiul]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Auditors: @bsclifton @bbondy

Fixes #6050

Test Plan:

1. Disable "worldWidePanel"
2. Open about:preferences#payments
3. Click the top left corner of "Cubits" button
4. Enable "worldWidePanel"
5. Open about:preferences#payments
6. Click the top left corner of "buybitcoinworldwide.com" button

[jkup]

This could probably just be an anchor, right?

[luixxiul]

Because having button element here maintains the consistency (the other buttons on the modal have been replaced from span to button) I think we should keep it.

[bsclifton]

After reviewing, I believe the same change needs to be made here:
https://github.com/brave/browser-laptop/pull/6051/files#diff-e3eeb751016b2ce9f8278efce585a461R373

I ran into the same issue when I was shown the buybitcoinworldwide.com button (I was unable to click the edges).

Since I'm in the US (which would usually show Coinbase), I tested by reversing these two values:
https://github.com/brave/browser-laptop/pull/6051/files#diff-e3eeb751016b2ce9f8278efce585a461R489

[luixxiul]

Updated, thanks @bsclifton :-)

[bsclifton]

Works great, thanks! 😄