t/zbd: Add test #58 to test zone reset by trim workload

To exercise zone reset by trim workload, add the test case #58. As the
precondition, it fills several zones. After that, a trim job and a write
job run in parallel for 30 seconds. The ratio of trim commands and write
commands is controlled by --flow option.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>