Description

Fix #14065 lib mode hanging for umd build, by using string manipulation instead of regex

Additional context

The original fix #7948 used regex for string replacement to avoid global esbuild helpers.

It has since caused multiple performance issues #8738 #8099 #10900 #14065, and received numerous attempts #8110 #8741 #10905 at fixing it, but there're still unhandled cases:

• UMD build, minify: true https://stackblitz.com/edit/vitejs-vite-9frvl5?file=vite.config.ts,index.tsx&terminal=build
• UMD build, minify: false https://stackblitz.com/edit/vitejs-vite-z5wdig?file=vite.config.ts,index.ts&terminal=build

I think this shows that regex isn't the right solution in this scenario. It's easier to manipulate the string directly, at the cost of a few extra lines.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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