Fix initial_tasks.json triggering diagnostic warning (#36523)

`zed::OpenProjectTasks` without an existing tasks.json will recreate it
from the template.
This file will immediately show a warning.

<img width="810" height="168" alt="Screenshot 2025-08-19 at 17 16 07"
src="https://github.com/user-attachments/assets/bbc8c7a0-7036-4927-8e85-b81b79aeaacb"
/>

Release Notes:

- N/A
b7dad2cf71Peter Tripp committed on 8/26/2025, 1:41:57 PM· committed by GitHubparent76dbcde
2 files changedLine totals unavailable