If you really believe your hosting provider puts root backdoors in your systems, you really shouldn't run anything in a hypervisor controlled by them.
> In order to be able to intervene on your dedicated server without your root password, the automatic installation of ssh key is done. Only authorized employees of OVH will use it. It is not a gap in security, contrary, thanks to this OVH has root rights to your server and may identify the problems with your server. When you request an intervention, we need to have access to ssh.
A static SSH key for a single human is already risky over a long time period, but for a key that is shared between multiple humans... wow.