chore(surveys): add surveys opt in to onboarding ingestion

[liyiy]

Problem

Add surveys snippet to onboarding ingestion so we can have it default on

Changes

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How did you test this code?

[raquelmsmith]

Interesting, why does surveys have to be opted in to?

[liyiy]

Interesting, why does surveys have to be opted in to?

This is a good summary for it! https://posthog.slack.com/archives/C034XD440RK/p1697434622931679

basically: we want to be explicit to the new user about surveys being turned on for them. It's a similar setting to the opt_in_site_apps setting we previously had

[neilkakkar]

It unnecessarily increases the package size for teams that don't use surveys. We only load all the js if they opt in.

So, I wonder if it's worth saying this more explicitly in onboarding? The only big reason tbh not to have it hidden + default on. But we don't say the same for session recordings here, which seems to work fine + those who care come back to turn it off, so LGTM!