qemu.test: add missed param for block_stream test

add 'tmp_dir' parms for block_stream test;

Signed-off-by: Xu Tian <xutian@redhat.com>
qemu.test: adjust block streaming test parms

increased default wait streaming finished timeout values to avoild test
failed when test big image;

Signed-off-by: Xu Tian <xutian@redhat.com>