The parameter isn't actually deprecated, since we need to support older
API microversion, however, we now emit an error if someone attempts to
boot a server with the wrong microversion. This would happen server-side
anyway since this parameter was removed entirely in API microversion
2.57.
Change-Id: I73864ccbf5bf181fecf505ca168c1a35a8b0af3a
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>