docs: Information inconsistency between 2 guides

[BlueCutOfficial]

The Setup document says:

For ember apps that still have an ember-cli-build file, this plugin comes built-in (...) provide it the desired configuration in ember-cli-build.

Then the Migrating document implies that we are migrating an Ember app using v3 or v4, which should have an ember-cli-build. But it provides a Vite Minimal Config that relies on the Babel config rather than ember-cli-build.

The issues I see are the following:

1. The wording should be more clear about what enables relying on the Babel config: is it "Babel config exists (because Vite)" or is it "ember-cli-build does not exist", or actually none of the options because it's slightly more subtle.
2. I think the meaning of Vite Minimal Config is part of the problem because it's not necessarily clear what "Minimal" means in the context of the latest Ember ecosystem. If you try to use the Babel config from the moment you're in a Vite app, it conflicts with babelCompatSupport(), and I easily imagine people doing that.

So my intuition is that Vite Minimal Config shouldn't be provided at all in the Migrating guide, which makes the text from the Setup the valid one.