This oplog sampling test inserts just enough documents to clear the sampling threshold of 2000. However, the oplog stones logic relies on the size storer to decide whether to scan or sample the oplog. Occasionally, the test fails to select the sampling logic due to a small difference (we've seen values of 1990 when the actual collection count should be 2020) between the size storer count and the actual collection count.

We can make this test run more robustly by choosing a higher number of documents to insert to clear the scanning threshold comfortably even when the size storer is not 100% accurate.