Replace GSD dep with ESD

It looks like we depend on GSD right now for the volume step dconf key? If we want this still, we should add this setting to ESD I think? Or drop it. But getting rid of this extra runtime dep on GSD would be good

Start by locating the GSD runtime dependency and the volume-step dconf key, then inspect how ESD could provide the setting. Done means either the setting is supported through ESD or it is removed, and the extra GSD runtime dependency is gone.

Written by the indexing model from the issue text.