Generally, the expectation when adding an override to a suite .yml is that this override applies broadly.

However, concurrency suites (FSM) do not actually apply the overrides to the worker threads, only to the master (runner.js). Instead, we have duplicated logic where overrides are injected explicitly in the worker_thread.js by inspecting TestData parameters or session state (or alternatively by specifying fsmPreOverridesLoadedCallback, but currently no suite in master uses this).

This makes understanding what a suite is actually doing very confusing. We should either generalize overrides to apply to worker threads transparently (similar to 
OverrideHelpers.prependOverrideInParallelShell) or somehow make it clearer that yml defined overrides (example) do not actually apply to worker threads in FSM suites.