ai_onboarding: Send users directly into the trial checkout flow when starting the trial (#34859)

This PR makes it so users will be sent immediately into the trial
checkout flow (by hitting zed.dev/account/start-trial) when they click
the "Start Pro Trial" button.

Release Notes:

- N/A
5289b815feMarshall Bowers committed on 7/21/2025, 11:58:16 PM· committed by GitHubparent8515487
2 files changedLine totals unavailable