fix: clean up two factor

[zlwaterfield]

Changes

There's currently a race condition introduced here https://github.com/PostHog/posthog/pull/26813/files that may double trigger the set up call and make it so the QR code being rendered doesn't match the token stored in the session.

This PR also cleans up the set up code so the modal is only rendered once and not in 3 locations.

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

Does this work well for both Cloud and self-hosted?

It doesn't have an impact.

How did you test this code?

Manually.

I'd love for the review to pull this locally and test all 3 cases to make sure it's all working

1. Set up 2FA from profile
2. Set up 2FA from members list (click on 2FA not enabled tag)
3. Turn on the 2FA enforcement on the organization, reload and set it up via the forced modal.

[github-actions]

Size Change: 0 B

Total Size: 1.11 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	1.11 MB

_{compressed-size-action}

[surbhi-posthog]

I see failing tests, so I'm just going to re-run them to see if they pass

[raquelmsmith]

I was wondering if a race condition would happen here..

Approving because my one comment is non-blocking but it might be better to change it up a bit.

[raquelmsmith]

I feel like this is confusing because the modal could be already open (if it's forced open), yet we're saying here to open the modal. but instead of it opening the modal, what's actually happening is this side-effect where startSetup is called.

I think it technically works but it's confusing and took me a bit to understand the code.