Is there actually any way to avoid getting insta-killed from too many shard stacks (or a way to avoid getting too many stacks/to clear stacks), or do I just need to keep plenty of revival items on me when I plan fighting them?

If you use an earth tank, then eventually with the right application of high enough rank moves you can shrug it off.
Using light's 4th move when the golem is at 85 mana is also viable, instantly reviving the tank when the KO happens

But the most common strategy is just playing, as they say, hot potato.
When a golem is at 85, if your tank has the slash-looking shards debuff icon, swap them to a different slot so they don't get the exploding shards debuff also.
The golem's exploding shards gets a multiplier when it and the slash-looking debuff are both on the same pet, so this neutralizes the majority of the move output