Leaded llamas keep spitting at the player when they switch gamemodes

Llamas that are leaded (e.g. attached to a fence or by a mob/player) will continuously spit at the player when they are attacked even when the player switches gamemode. This doesn't happen with any other mob or when the llama isn't on a lead.

Relates to MC-208315, MC-215097, and MC-154053

Steps to Reproduce:

1. Attach a lead to llama and attach it to a fence
2. Attack the llama in survival mode
3. Switch your gamemode into Spectator or Creative mode.
   The llama continues to spit on you while you are not in survival mode