tests: fix race condition on macOS

[dunglas]

No description provided.

[Copilot]

Pull request overview

Updates the Caddy integration tests to reduce macOS flakiness by ensuring the test server is actually accepting connections after InitServer, addressing transient SO_REUSEPORT routing to a shutting-down listener.

Changes:

• Introduce an initServer helper that calls tester.InitServer and then polls the HTTP endpoint to avoid early “connection reset by peer” failures.
• Replace direct tester.InitServer(...) calls throughout the file with initServer(...).
• Remove now-redundant waitForServerReady(...) calls in tests that previously needed extra readiness polling.

Comments suppressed due to low confidence (1)

caddy/caddy_test.go:43

• initServer returns silently if all 10 polling attempts fail, so tests may continue with the server still unavailable and fail later with less actionable errors. Consider failing the test after the retry loop (e.g., t.Fatalf/require.FailNow) and include the last error/URL in the message so readiness issues are surfaced immediately.

	url := "http://localhost:" + testPort
	client := &http.Client{Timeout: 1 * time.Second}
	for range 10 {
		resp, err := client.Get(url)
		if err == nil {
			require.NoError(t, resp.Body.Close())

			return
		}

		time.Sleep(100 * time.Millisecond)
	}
}

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