chore: Remove Demographics frontend components from edx-platform (#35121

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[APER-2823]

Removes React compoents and functionality tied to a private 2U/edx.org-specific Demographics IDA from edx-platform.

This PR attempts to remove everything added from this PR: #24956. This includes the React components created to collect and transmit Demographics data, as well as functionality for managing JWT and CSRF tokens copied from `frontend-platform` to edx-platform when originally implementing the CTA and modal components.