fix race condition in getting floating ip
fix race condition in getting floating ip

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