chore: add a flag to disable local login while setting up

[siddharthsarda]

The issue is described here: https://community.nodebb.org/post/90464. I want to be able to control local login when deploying NodeBB on a managed container service like AWS Apprunner. ./nodebb setup always grants local login privileges even if the database has them disabled (probably because they are booleans with the default as false, not ideal for most cases)

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