ansible: stop promotion if missing assets

[RafaelGSS]

As discussed in the release channel, this should prevent people unfamiliar with this state from wrongly promoting a Node.js version.

Refs: nodejs/node#60176

[RafaelGSS]

ping @nodejs/build

[aduh95]

We should probably give a way to override this if need be, no?

[richardlau]

We should probably give a way to override this if need be, no?

Presumably that would either be:

• A y/n question to the releaser, which brings us back to the current situation -- the default of the current set up is to not promote and the releaser has to answer "y" (i.e. affirmative action).
• Someone in build reverting this change and the releaser trying again. As a Build WG member I'm not overly enthused by that possibility.

I'm on the fence as to whether this is needed, and will go with the Release WG consensus.