fix: fix unsubscribe survey typo

[xrdt]

Problem

There was a typo in the logic for checking whether the survey response was empty that was causing us to send 'survey dismissed' instead of 'survey sent' events.

Changes

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

How did you test this code?

[raquelmsmith]

🙈 should we do a cypress test for this to make sure it actually works as we expect?

[github-actions]

Size Change: 0 B

Total Size: 2.01 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	2.01 MB

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[xrdt]

🙈 should we do a cypress test for this to make sure it actually works as we expect?

Tabled the cypress testing for now as it's not quite obvious how to intercept posthog.capture calls from posthog. Slack thread: https://posthog.slack.com/archives/C0113360FFV/p1699982765367859