What stops the farming in MOBA games is a surrender option. You get less money from it, but its better than staying in thr game getting whooped. As on LoL, the surrender option isn20 minutes in. Stop you cant just surrender whenever because your team feels like it.
For Halo, just add a surrender option on the menu in warzone and the clear notification to go to the menu and surrender. This wont stop kill farming, but it will stop it more early rather than staying in the game and die constantly or leaving and risk getting ban.