selftests: ublk: add batch IO cases to recover_03

Add -b coverage for quiesce recover.

Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Link: https://patch.msgid.link/20260821103047.369522-3-yangxiuwei@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>