The functions defined with the $config object of an FSM workload are executed by multiple threads in the following way:
1. The $config.setup() function is executed once by the main thread.
2. The $config.states functions are executed $config.iterations times by each the worker threads.
3. The $config.teardown() function is executed by the main thread.
The changes from
SERVER-30681 made it so a session is started with causal consistency enabled for each of the FSM worker threads. The changes from SERVER-30682 made it so that a readPreference of "secondary" is used, which made it possible for the $config.setup() function to do a write to the primary and for a $config.states function to do a read from a secondary. The main thread must forward its operationTime and clusterTime after #1 to each of the worker threads to ensure that a read from secondary will wait until the write has been applied.