Remove unused flag gcp_preemptible_status_bucket.
Remove unused flag gcp_preemptible_status_bucket.

PiperOrigin-RevId: 362990652

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