fix flaky test-fs-stat-bigint

[Trott]

• Version: v11.0.0-pre (master)
• Platform: macOS but probably all
• Subsystem: test

test-fs-stat-bigint is flaky due to side effects. One test case can affect the outcome of another test case. @samarthgulati is working on a fix. This is just here to document some stuff until they get a PR in, hopefully in the next hour or so.

[Trott]

When the previous stress test finishes, https://ci.nodejs.org/job/node-stress-single-test/1971/ will be the URL for a stress test that will (hopefully) show the flakiness.