Describe the bug

After upgrading vite, the build.minify configuration is invalid, minify is disabled in lib mode, and it was available before. This configuration is confusing, I found the reason, I hope to keep this feature, it is very useful to me. I don't want to write an additional Rollup plugin for this requirement, I hope there are other simple solutions.
vuejs/core#2860 (comment)
06d86e4

Reproduction

// vite config
{
  "build": {
    "minify": true,
    "lib": {
      "name": 'vue',
      "entry": 'vue.js',
      "formats": ['es'],
      "fileName": () => `vue.js`,
    }
  },
}

System Info

System:
    OS: Linux 5.4 Ubuntu 21.10 LTS
  Binaries:
    Node: 16.10.0 - ~/.nvm/versions/node/v16.10.0/bin/node
    npm: 7.24.0 - ~/.nvm/versions/node/v16.10.0/bin/npm
  Browsers:
    Chrome: 95.0.4638.54
  npmPackages:
    @vitejs/plugin-vue: ^1.9.3 => 1.9.3 
    vite: ^2.6.4

Used Package Manager

pnpm

Logs

No response

Validations

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• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/vue-next instead.
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• The provided reproduction is a minimal reproducible example of the bug.