test: fix server hmr port conflict

[sapphi-red]

Description

Similar to #7523 but for hmr port.

Ideally, it should use the next unused port instead but it will require more work so I didn't do it in this PR.
Also I feel it curious to silent EADDRINUSE for ws server. 🤔

vite/packages/vite/src/node/server/ws.ts

Lines 162 to 169 in 0858450

	wss.on('error', (e: Error & { code: string }) => {
	if (e.code !== 'EADDRINUSE') {
	config.logger.error(
	colors.red(`WebSocket server error:\n${e.stack || e.message}`),
	{ error: e }
	)
	}
	})

Steps to reproduce

1. Edit playground/ssr-react/server.js line 90 app.listen(5173, () => { to app.listen(5174, () => {.
2. Run pnpm dev in playground/ssr-vue
3. Run pnpm dev in playground/ssr-react
4. Edit playground/ssr-react/src/pages/Home.jsx
5. HMR does not happen

Additional context

It does not affect CI because only one thread is used with CI.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[bluwy]

Nicee it's working for me too. Maybe it's still worth looking into auto-increment the the hmr port, but I think this is fine for now to get local tests running properly. And also, maybe this is the reason we can't run multiple threads on CI? So we can tune it up now 🤔