docs: revert "Update authentication docs to use useActionState (#72503)"

[JamBalaya56562]

What?

Back out "Update authentication docs to use useActionState (#72503)" commit.
Original commit changeset: d4136d9

Why?

The useActionState Hook is currently only available in React’s Canary and experimental channels.
We should use useFormState until React 19 is stable.

x-ref: docs: Use useFormState over useActionState #69547

Improving Documentation

• Run pnpm prettier-fix to fix formatting issues before opening the PR.
• Read the Docs Contribution Guide to ensure your contribution follows the docs guidelines: https://nextjs.org/docs/community/contribution-guide

[ijjk]

Allow CI Workflow Run

• approve CI run for commit: a3be3cf

Note: this should only be enabled once the PR is ready to go and can only be enabled by a maintainer

[delbaoliveira]

Hey @JamBalaya56562! 👋🏼

Since v15 is now the latest stable version and using React 19 canary, you'll get a warning when using useFormState. We mention the hook update in our docs (here).

I'll close your PR because the stable version React 19 is coming soon (👀), so we don't have to duplicate the work. We'll also need to update any other mentions of useFormState to useActionState.