t/zbd: Combine write and read fio commands for test case #15

t/zbd: Combine write and read fio commands for test case #15

The test case #15 called fio twice. Once with write job to prepare data
to read. The other with read job for testing. But the first run has no
effect on the second run when the zone status is reinitialized.

Specify both the write job and the read job to a single fio command using
write_and_run_one_fio_job() helper function instead of run_one_fio_job().

Also apply same test pass condition for both regular block devices and
zoned block devices.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>