Deprecate LazyImage for 2.x, remove it for 3.x

The [documentation already mention that LazyImage is no longer recommended](https://github.com/symfony/ux/blob/2.x/src/LazyImage/doc/index.rst), but I believe we can make it more "official".

- [X] Deprecate https://github.com/symfony/ux/pull/2813
- [x] Remove https://github.com/symfony/ux/pull/2994