cleanupOrphanedWhileMigrating.js performs a cleanupOrphans that in case of stepdown on a slow machine might delay to point to cause the assert soon to trigger.

A real example of a broken interleaving coming from BF-29780 that causing the test to fail 

• A cleanupOrphans runs on a primary
• the primary becomes secondary
• cleanupOrphans fails after 5
• The operation retried due to assert.soonNoExcept
• A cleanupOrphans runs on a primary
• the primary becomes secondary
• cleanupOrphans fails after 8s
• assert.soon triggers timeout

Increasing the timeout could mitigate but not fix the issue: In assert.soonNoExcept we re-run the command until success or until we hit the timeout. The test could keep failing if  step-down keeps occurring at every attempt