fix: remove useless set-cookie in action-handler (#76839)
`handleAction` had a weird spot where it'd add a `set-cookie` header if
a redirect was thrown during handling a no-js action. AFAICT, this is
unnecessary -- we set the `set-cookie` header on the response as soon as
`cookies().set()` is called, so there's no need to set the cookies again
in that branch of the handler.
this is done through a combination of the patched setter from
`RequestCookies`:
https://github.com/vercel/next.js/blob/0abd87717f19bced6c35af1255837628513cf772/packages/next/src/server/web/spec-extension/adapters/request-cookies.ts#L160-L171
and this cookie updating function from the request store (which
`updateResponseCookies` above would invoke with the new cookies):
https://github.com/vercel/next.js/blob/0abd87717f19bced6c35af1255837628513cf772/packages/next/src/server/async-storage/request-store.ts#L170-L174
i've also added a test for this specific scenario to ensure that this
wasn't actually doing anything useful.
