when using --disable_smt, do not reboot if threads_per_core is already 1
when using --disable_smt, do not reboot if threads_per_core is already 1

PiperOrigin-RevId: 355771615

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