Use correct class name for Link when disabling it for Checkout editor page

[senadir]

This is a follow up to #3516 in which a refactor I made at last moment made that PR useless. This PR fixes that.

Testing instructions

1. Ensure Link is working fine.
2. In Checkout editor page, Link shouldn't show as not compatible.

[james-allan]

This looks good to me.

I noticed while testing that I was stilling seeing an incomplete notice.

^{"" does not yet support this block}

I found in the previous PR that this is being fixed in WC core via woocommerce/woocommerce#52070. It will now use the $title rather than $method_title.

That does make me wonder what the difference is between $title and $method_title and whether the fact that our payment methods which don't always set the $method_title may be missing. 🤔

From the WC_Payment_Gateway class definition, it looks like method_title is the backend title and title is the frontend. 🤷‍♂️ In any case we should probably tidy that up.

I also confirmed while on this branch that Link still works on the backend and frontend as you'd expect.

[senadir]

Yes I wasn't sure what's the different tbh and Link doesn't seem to have the method title, just the title. For our side, we try our best to find a title to show.