Remove onboarding script (#36203)

Just use `ZED_STATELESS=1 zed` instead!

Release Notes:

- N/A *or* Added/Fixed/Improved ...
3a711d0814Joseph T. Lyons committed on 8/14/2025, 7:19:37 PM· committed by GitHubparentb65e9af
1 file changedLine totals unavailable