Closes https://github.com/zed-industries/zed/issues/42360

If updating a language server takes longer than 10 seconds, we now fall
back to launching the currently installed version (if exists) and
continue downloading the update in the background.

Release Notes:

- Improved language server updates for slow connection, now Zed launches
existing server if the update is taking too long.

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Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>