fix: a regression in ntl serve with the package path

[lukasholzer]

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Summary

Fixes https://linear.app/netlify/issue/COM-549/monorepo-with-edge-functions-ssr-returning-404-since-cli-v-17193

Fixes a regression that was introduced with #6433

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[github-actions]

📊 Benchmark results

Comparing with 2c716d8

• Dependency count: 1,326 (no change)
• Package size: 298 MB ⬆️ 0.00% increase vs. 2c716d8
• Number of ts-expect-error directives: 1,112 ⬇️ 0.72% decrease vs. 2c716d8

[ascorbic]

Confirmed that this fixes the issue. Thanks