We conduct a lot of signature checking during the build.

We do this following the individual signature, after dual signing, and again during a custom test step.

The custom test step reimplements the Nvidia install script, and is duplicative of what was installed during common/extra builds.

I think we are doing a bit of belt and suspenders paranoia here, and part of that is exposing dual sign as being optional.

I think we need to rethink how we include scripts so that we can reuse them during the test stage and not maintain a second, duplicate test step.