fix: only print prerender progress newline when necessary

[Rich-Harris]

Fixes a small bug introduced in #16750 — the moveCursor and clearLine calls were themselves being intercepted, so mid_line was always true, and we'd just print newline after newline

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[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from ce3ba15:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/ce3ba154bbda40c8c23fa17844491f9d63f2ed27

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16766

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Latest commit: ce3ba15

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