http api: T1431: update args of call to install-image
http api: T1431: update args of call to install-image

commit 3f8884587 added an endpoint for image management; T2753 updated the
command line options. Make script call consistent.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x