fix: move Vitest.setServer to post configureServer hook to enable import analysis for workspace config loading

[hi-ogawa]

Description

• Closes import statements within vitest.workspace can't import .ts files using the .js extension #6519

As @sheremet-va suggested in #6519 (comment), this moves two configureServer hooks to order: "post". Reviewing with "Hide whitespace" is recommended.

This technically works, but I have an uneasy feeling that this is fragile. Alternatively I'm thinking we can load vitest.workspace.ts using a fresh vite server instance similar to how astro loads config https://github.com/withastro/astro/blob/2594eb088d53a98181ac820243bcb1a765856ecf/packages/astro/src/core/config/vite-load.ts#L55-L65. This would ensure a well-determined (though restrictive) behavior of config loading.

That said, simply moving to order: "post" might good enough, so I think we can try this first.

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[hi-ogawa]

/ecosystem-ci run

[vitest-ecosystem-ci]

📝 Ran ecosystem CI: Open

suite	result
aria-live-capture	✅ success
nuxt	❌ failure
nuxt-test-utils	✅ success
elk	✅ success
effect	✅ success
zustand	✅ success
vue	✅ success
vite	✅ success
vitest-vscode	❌ failure
vitest-sonar-reporter	✅ success
vitest-github-actions-reporter	✅ success
vitest-browser-simple	✅ success
vitest-browser-examples	✅ success
vitest-coverage-large	✅ success
vitest-reporters-large	✅ success
vitest-benchmark-large	✅ success

[hi-ogawa]

Btw, I also tried moving it to "post middleware" hook like below, but it turns out Vite doesn't await returned promise so it didn't work https://github.com/vitejs/vite/blob/95020ab49e12d143262859e095025cf02423c1d9/packages/vite/src/node/server/index.ts#L881-L884

{
  configureServer(server) {
    return async () => {
      await ctx.setServer(options, server, userConfig)
      ...
    }
  }
}