iotests: replace qemu_img_log('create', ...) calls

iotests: replace qemu_img_log('create', ...) calls

qemu_img_log() calls into qemu_img_pipe(), which always removes output
for 'create' commands on success anyway. Replace all of these calls to
the simpler qemu_img_create(...) which doesn't log, but raises a
detailed exception object on failure instead.

Blank lines are removed from output files where appropriate.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220321201618.903471-17-jsnow@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>