Clean up the recently-added aka.ms fallback logic when aka.ms links are updated

[baronfel]

In #554 we implemented a fallback logic for aka.ms links that pointed to azureedge urls that would attempt to locate the same asset on the newer CDN feeds. This was done to help users seamlessly use and stay on the new CDNs, while also delaying the need for the release team to update the many aka.ms links.

The links are scheduled to be updated soon - when that happens, we should remove the rollback logic.