Yes, that deleted scene appears in the TV "Saga" version. But, there's no mention of Luca in the novel.
There's a fascinating part of the novel that traces the Don's rise.

SPOILER ALERT!!!

He gets involved in a war with Maranzano, who asks Capone for help. Capone sends two gunsels, but Luca meets them at the train station, captures them at gunpoint, takes them to a warehouse--and uses an axe to chop off their legs! That's probably why so many people believe that Luca did in the horse. As I said in an earlier post: the fact that Luca wasn't mentioned in the novel in connection with the horse decapitation doesn't necessarily mean he wasn't involved.