feat: show warning to discourage putting process/global to define option

[sapphi-red]

Description

I've been seen many people doing define: { global: 'window' } and breaking their apps.
Ideally it'd be better to improve how define works, but I think having a warning until that's implemented is nice.

• Can I an api with the endpoint of "/global"? #14445
• vite dev works but vite build fails to import a project file #14191 (comment)
• Global define applying too liberally #13237 (comment)
• Defining global object in vite config breaks any imports with global in their name #12814
• Define field in vite.config overwrites values inside of strings #9720
• Defining global: 'globalThis' variable will replace global.css as "globalThis".css on building #4796
• vite build fail when use define #2700

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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