yield_with_drop.js FSM test is performing several concurrent  drop/re-create/createIndexes. Thus, it can happen that the router extinguish the 10 retry attempts while attempting to execute the createIndexes command.

In particular, consider the following scenario:

• thread_0: createIndex -> CannotImplicitelyCreateCollection
• thread_0: createCollection -> OK
• thread_1: dropCollection
• thread_0: createIndex -> CannotImplicitelyCreateCollection or StaleConfig
• thread_0: createCollection -> OK
• thread_1 dropCollection
  etc....

Thus, we should add both StaleConfig and CannotImplicitelyCreateCollection errors to the list of expected errors.