perf_stream: add option to test file_open_options::sloppy_size
perf_stream: add option to test file_open_options::sloppy_size

dreamsxin/seastar,avikivity/seastar,syuu1228/seastar,kjniemi/seastar,scylladb/seastar,syuu1228/seastar,cloudius-systems/seastar,cloudius-systems/seastar,scylladb/seastar,syuu1228/seastar,avikivity/seastar,cloudius-systems/seastar,scylladb/seastar,dreamsxin/seastar,kjniemi/seastar,kjniemi/seastar,avikivity/seastar,dreamsxin/seastar