fix: address flaky integration tests

[jaredm563]

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Summary

Fix 1:

Multiple file watcher events (onAdd, onChange) could trigger concurrent build() calls, causing race conditions where the bundler accessed functionConfigs[name] before it was populated .

now only one build runs at a time, and when the current build completes, it checks buildPending and runs another build if needed

Fix 2:
tests/integration/utils/dev-server.ts waited up to 90s with no useful error message, now on timeout it should shows the actual server output so far for debugging

Fix 3:
In tests/integration/commands/init/init.test.ts answerWithValue(CONFIRM) sent ['\n', '\n'] (two newlines), which was causing the second newline to answer the wrong prompt.

Now it should use a single CONFIRM for list/confirm selections, so that prompts are answered correctly and the netlify.toml gets created

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[github-actions]

📊 Benchmark results

Comparing with 4a57375

• Dependency count: 1,055 (no change)
• Package size: 317 MB (no change)
• Number of ts-expect-error directives: 366 (no change)

[serhalp]

Don't sink your day into this, but could you take a few mins to see if we can avoid adding all these @ts-expect-errors? 🙏🏼