Refactor: remove deprecated insight/list routes that use old access model

[jpmcb]

Type of feature

🧑‍💻 Refactor

Current behavior

As a followup to: https://github.com/open-sauced/api/issues/634 and #635 we'll want to refactor (and remove) the old insight/list endpoints that use the old auth/access model.

For example, in the v2/user/insights/${id} endpoint:

https://github.com/open-sauced/api/blob/7e86446487333657584c97832e2aab9f1479eb97/src/insight/user-insight.controller.ts#L96-L97

Suggested solution

Remove code in those routes.

This would technically be a breaking change to the API. We should handle that appropriately before removing those routes.

Additional context

No response

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