Pigs are pretty omnivorous by nature, but many animals we think of as herbivores will eat meat and bones sometimes, maybe for the mineral content.
Hippos are known to eat carcasses, and sometimes fresher meat, as well. Killing someone and feeding them to the hippos might not work for most story settings, though.
Domestic dogs will even eat human bodies if they're hungry enough (loyalty to one's human pack only goes so far). I believe this happened during the Irish Potato famine and the black death and other historical times when people were dying en masse and there were packs of feral, hungry dogs running around. I have little trouble believing ravenous porkers might consume a human body, though I don't know of they really eat
all the bones.
I poked around a bit on the web to see how common it is for pigs to actually eat humans and whether or not they really do consume all the bones and found a lot of anecdotal and apocryphal information, but nothing that was extensively documented. It's a common enough trope in media that it has a TV tropes entry, but so do many things that are over stated or completely untrue. There are many historical accounts of pigs eating human bodies, including during the genocides in Serbia, but it's harder to document whether or not they typically leave no trace at all. Wild pigs scavange, though, so it makes sense they'd have adaptations that allow them to eat body parts other animals might have passed over.
I do know that pig toilets are a real thing in some parts of the world. I don't know if the pigs used to dispose of human waste were also eaten by humans. I hope not.
https://en.wikipedia.org/wiki/Pig_toilet