GPRD Postgres transaction rollback rate is high

I got an alert about Postgres transaction rollback rate is high for postgres-01 on gprd. Upon investigation there are a LOT of wal-prefetch wal-e processes. The load on the box is about 100-120 (on 32 cores). However, the WAL files seem to be consumed correctly, there are just a substantial amount of them going at one time.

I'm unsure what to do here, as there doesn't seem to be anything broken, just an absurdly high load. The load has been this high since March 23.

This may not even be anything, but it is noisy and we should at least consider modifying the alert threshold.

cc/ @_stark @jarv @ahmadsherif @eReGeBe