Fix guardian fish smelting loot warning

[Heroluex]

Description

This fixes a warning caused by Guardian and Elder Guardian bonus fish loot applying minecraft:furnace_smelt to the entire minecraft:gameplay/fishing/fish loot table.

That nested fish loot table can roll pufferfish and tropical_fish, which do not have smelting recipes. When a Guardian is on fire or killed with an enchantment in #minecraft:smelts_loot, the server attempts to smelt those items and logs a warning.

This change applies minecraft:furnace_smelt only to cod and salmon.

[Lulu13022002]

Can you update the data generator too with a mention of MC-248508 to keep the output consistent with what's in the server.

[Lulu13022002]

actually I'm not sure it's worth fixing it before mojang given this would break datapack changing the nested loot table and expecting it to work for those mobs and the warning is harmless.