Add configurable flag for SMBIOS status polling timeout.

On platforms where OS state transitions to Standby immediately at DC power-on, `smbios-mdr` can take ~3 minutes to finish POST and push `"NEW"` to the SMBIOS status file, exceeding the default 2-minute (120s) polling timeout in `FruCollector::PollSmbiosStatus`.

This change adds `--smbios_blob_timeout_sec` flag (defaulting to 120 seconds) to replace the fixed 2-minute timeout.

#deterministic-bmc

Google-Bug-Id:565581423
PiperOrigin-RevId: 991092083
Change-Id: Ice695cfa7b0792c543abfd13df9e19635245f7ce