Move default configuration settings to the app

[evan-forbes]

Currently we are overriding a few default configurations during the init command. We should move this to the app so that the settings we change are more explicit and don't require changes to the sdk.

[liamsi]

Yeah, I was also confused about this. Either these default param changes can be made directly in core, or, in app. App is the best if feasible 👍🏼

[rootulp]

I think most of the default overrides have been moved to celestia-app's default_overrides.go. I think the remaining revertable overrides that can be moved to celestia-app are documented here.