Comment 3 for bug 1780834

I don't want spam.installed.core being set super early, because that would be a lie; we don't want any snaps installed, including core, until an installation request is made.

I think deferring change_snapd_refresh until the snap.installed.core state is set is fine. And needs to be done in any case, since I expect 'snap set core' to fail if it is called before the core snap is installed, and we need to defer that happening until we know we actually want a snap installed.