The concurrency suites with balancer and failovers previously set this value (see SERVER-90217) but the parameter was removed in SERVER-94696. Not setting this parameter in the suite results in a default value of one second (set here or here). The default value of one second is too short as it can result in inconsistent secondary reads as described in SERVER-87673.  The concurrency suites with balancers and failover should re-set this value again to avoid intermittent test failures from inconsistent secondary reads.