Fix benchmark spec tests to pass benchmark name to constructor.
Fix benchmark spec tests to pass benchmark name to constructor.

mateusz-blaszkowski/PerfKitBenchmarker,mateusz-blaszkowski/PerfKitBenchmarker,kivio/PerfKitBenchmarker,kivio/PerfKitBenchmarker,AdamIsrael/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,syed/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker,meteorfox/PerfKitBenchmarker,AdamIsrael/PerfKitBenchmarker,syed/PerfKitBenchmarker,GoogleCloudPlatform/PerfKitBenchmarker