Add deprecation warning for legacyBehavior prop (#77473)
We plan to remove this feature in v16. The deprecation warning includes
a link to the docs and an example of how to run a codemod.
<img width="976" alt="Screenshot 2025-03-24 at 12 51 05 PM"
src="https://github.com/user-attachments/assets/e044e143-f88a-4f24-bb94-4dd8b46f6288"
/>
