fix: issues with analytics not sending userID

[brainbicycle]

This PR resolves PHIRE-1082

Description

We were initializing the segment client 2x - once in App.tsx and once in AppRegistry, the identify call was happening during auth flow so when segment client was reinitialized it blew away the saved user id. Seems only became a problem after the update to the analytics library.

PR Checklist

• [ ] I have tested my changes on iOS and Android.
• [x] I hid my changes behind a feature flag, or they don't need one.
• [x] I have included screenshots or videos, or I have not changed the UI.
• [x] I have added tests, or my changes don't require any.
• [x] I added an app state migration, or my changes do not require one.
• [x] I have documented any follow-up work that this PR will require, or it does not require any.
• [x] I have added a changelog entry below, or my changes do not require one.

To the reviewers 👀

• [ ] I would like at least one of the reviewers to run this PR on the simulator or device.

Changelog updates

### Changelog updates #### Cross-platform user-facing changes - #### iOS user-facing changes - #### Android user-facing changes - #### Dev changes - fix analytics not being tied to user ids - brian

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[ArtsyOpenSource]

This PR contains the following changes:

• Dev changes (fix analytics not being tied to user ids - brian)

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