Change stylistic ESLint TypeScript defaults (#78679)
As discussed stylistic ESLint defaults should not be errors they should
be warnings instead as errors from ESLint should be serious as they
cause builds to fail. If users want to be more strict they can make them
errors themselves.
x-ref: [slack
thread](https://vercel.slack.com/archives/C088NDH88AY/p1745893026311189?thread_ts=1745871583.511739&cid=C088NDH88AY)
