[Chore] Deprecate and remove user.segment

[AbhiPrasad]

Description

As per https://github.com/getsentry/sentry/issues/58767#issuecomment-1808116241, user segment is deprecated from the user interface and the SDK.

Let's work to remove support for this across the SDKs.

### Tasks
- [ ] https://github.com/getsentry/sentry-javascript/pull/10210
- [ ] https://github.com/getsentry/sentry-php/pull/1681
- [ ] https://github.com/getsentry/sentry-python/issues/2718
- [ ] Ruby SDK
- [ ] Go SDK
- [ ] https://github.com/getsentry/sentry-java/issues/3497
- [ ] https://github.com/getsentry/sentry-cocoa/issues/4090
- [ ] https://github.com/getsentry/sentry-cocoa/issues/4093
- [ ] https://github.com/getsentry/sentry-dart/issues/2115
- [x] React Native
- [ ] .NET SDK

RFC

No response

Slack-Channel

No response

Notion Document(s)

No response

Stakeholder(s)

@AbhiPrasad

Team(s)

Mobile, Web Backend, Web Frontend

[krystofwoldrich]

For RN, it was deprecated when deprecated in JS and will be removed in RN V6 (includes JS V8).