Attempting to make changes to this test causes burn-in tests to run (and fail) which means we cannot cleanly update the test until this is fixed.  Demonstrated with a patch that just adds a noop newline: https://spruce.mongodb.com/version/67e561343fd12f00078c55ae

The issue appears to be with the `FuzzRuntimeParameters` hook, we get this failure at the end:

[fsm_workload_test:create_index_background_unique] Sometime after completion of FSM workload jstests/concurrency/fsm_workloads/ddl/create_index_background/create_index_background_unique.js, the test outcome was changed to "fail" because: The hook FuzzRuntimeParameters failed.