Definitely not the start of the joke, but I couldn’t tell you where it did start. I think it long predates the internet. I would guess that it goes back to cultural conflict between British and French aristocracy in centuries past, but at this point I think it’s very far removed from the origins.
In the US, I think using France as the butt of random jokes got a boost during George W. Bush’s presidency because France publicly opposed the US’s invasion of Iraq, which caused some absurd and petty reactions from US politicians, like renaming “French fries” to “freedom fries”.
I have no idea why Disney decided to change that line. Perhaps it has more to do with the suggestion of interracial partnerships than with France specifically? Either way, Jesus Christ, Disney…