Fio: job file or command line.

[yuyantingzero]

Both fio_benchmark and block_storage_workloads_benchmark uses fio binary, but fio_benchmark uses job file, block_storage_workloads_benchmark uses command line.
It might be easier to maintain and understand if we only uses either job file or pure command line. Any preference?

[voellm]

@noahl - Is this still open with all the fio changes?

[noahl]

This is still open. I think the only solution that will work for all of our use cases is job files (and they're also more readable!), but I haven't converted the block_storage_workloads_benchmark yet. I want to take a broader look at whether fio_benchmark and block_storage_workloads_benchmark can share more common infrastructure than they do right now.