dillon1000/react

Move enableUseDeferredValueInitialArg to canary (#28818)

Per team discussion, this upgrades the `initialValue` argument for
`useDeferredValue` from experimental to canary.

- Original implementation PR:
https://github.com/facebook/react/pull/27500
- API documentation PR: https://github.com/reactjs/react.dev/pull/6747

I left it disabled at Meta for now in case there's old code somewhere
that is still passing an `options` object as the second argument.