Use a default referrer policy of no-referrer-when-downgrade (obsolete)

OBSOLETE: This policy is obsolete and doesn't work after Microsoft Edge 88. This policy doesn't work because it was only intended to be a short-term mechanism to give enterprises more time to update their web content if it was found to be incompatible with the new default referrer policy. Microsoft Edge's default referrer policy was strengthened from the value of no-referrer-when-downgrade to the more secure strict-origin-when-cross-origin. When this enterprise policy is enabled, Microsoft Edge's default referrer policy will be set to its old value of no-referrer-when-downgrade. This enterprise policy is disabled by default.