Change the double match logic in UnifiedDownloaderFactory
Change the double match logic in UnifiedDownloaderFactory

This changes the logic when checking how many clients have returned
valid for a query to explicitly ignore VSOClient iff there are two
matches and one of them is the VSOClient.

This changes it from the old behaviour where if there were any number of
matches the first subclass of GenericClient was used.

dpshelio/sunpy,dpshelio/sunpy,dpshelio/sunpy