This removes remaining references to `granularChunks` in configs, error messages, and comments.
Also removed the `process.env.__NEXT_GRANULAR_CHUNKS` value.
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Follow up to: https://github.com/vercel/next.js/pull/13663
Adding a conformance plugin the make sure users don't undo the benefits of the granularChunks config.
The plugin makes sure that minSize, maxInitialRequests values aren't overridden. Also ensures the cacheGroups - vendors, framework, libs, common, shared are maintained.
The warning and error messages do not break the build with this change. They only display a message.
cc - @prateekbh, @atcastle
