The shard split performance JS test was running shard split to verify the critical section takes under 500ms. It was removed in SERVER-89933 because there were transient failures and because usage of shard split is winding down.

The goal of this ticket is to add the test if we start using shard split again. We might also consider migrating the test to DSI to better handle edge cases where shard split takes longer (which was causing occasional redness).