Remove the 2U-specific @edx/brand-edx.org dependency from edx-platform

[jristau1984]

Maintenance WG identified this dependency in edx-platform. FedX thought it would be best implemented by Arbi-BOM. Thread is here: https://twou.slack.com/archives/C04ACK1PPNJ/p1739548762057589

Proposed approach by @adamstankiewicz:

Ideally, we'd have @edx/brand-openedx installed by default in edx-platform's package.json, under the @edx/brand alias. Then, our edxapp build scripts would need to ensure our 2U/edX.org specific brand package is installed under the same @edx/brand alias.

The first part of this ticket is to do some initial discovery to fully understand the request and define ACs. Any issues or questions should be brought up in team standup.