initUpdateInTransactionStates performs an updateOne by _id, where _id is not necessarily the shard key. This is known to produce incorrect results in presence of concurrent chunk migrations. While PM-3190 aims to fix this, this can cause test failures in older branches, and also when the feature flag is off. Moreover, it looks like PM-3190 has been rescoped to not fix this when retryableWrites are not used.

The test can be fixed by targeting the updateOne by shard key skey instead of by _id.