Mongot mock has created a couple of BFs due to a pinned connection unexpectedly closing before the test repeatedly pings that connection for an expected response

When planning PM-3512, we originally thought we would be able to retire the mock. However, due to both not having enough true e2e (eg with real mongot) coverage and also due to the nature of cross-repo work (hard to test e2e a feature if only one team's portion of the shared work is complete), we need to keep the mock for the time being. 

If this bug is not too difficult to fix on the mock, it would be ideal to fix on the mock. Otherwise, can just write kill_cursors.js to use a real mongot. The first part of this ticket should be investigating how difficult it would be to fix the mock.