Allow YCSB to adjust load dynamically.
Allow YCSB to adjust load dynamically.

PiperOrigin-RevId: 325851330

GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker