LONDON (AP) — Goodbye Twitter. Hello X. Elon Musk has unveiled a new “X” logo to replace Twitter's famous blue bird as he follows through with a major rebranding of the social media platform he bought for $44 billion last year. The X started appearing at the top of the desktop version of Twitter on Monday, but the bird was still dominant across the smartphone app. In response to questions about what tweets would be called when the rebranding is done, Musk said they would be called Xs. It's yet another change that Musk has made since acquiring Twitter that…