In SERVER-109544 it was discovered that setParameters can be persisted after a test ends, since the fixture doesn't reset after each run. This caused tests like histogram_ce_stability_pbt.js to make other tests fail by leaking the "planRankerMode: histogramCE" setting into a test which expects the default.

We should check other suites to see if they can carry over state. setParameters leaking is a significant risk, we could be getting different coverage than expected.

This ticket should also come up with a longterm solution for preventing unexpected state persisting between tests. Some options are

• Failing the test if it doesn't clean up setParameters and other state when it's complete.
• Setting CleanEveryN=1 in the passthrough fixture
• Banning setParameter in certain suites