Ensure HTTP response return codes are properly handled

[markushi]

We need to ensure that all SDKs treat successful HTTP responses from our backend the same way.
This means not just HTTP 200, but any HTTP 2xx response code should be treated as sucessful.

## SDKs
- [x] JavaScript https://github.com/getsentry/sentry-javascript/blob/c56d84de956981e959bcab672b8cce80217dc8f8/packages/core/src/transports/base.ts#L81
- [x] Python https://github.com/getsentry/sentry-python/blob/f5e964f9aeac7e8268e2034e2d5fcb70d8585251/sentry_sdk/transport.py#L371
- [x] PHP https://github.com/getsentry/sentry-php/blob/383514bb4326e1e229d9dff0c97ccfba55289225/src/Transport/ResultStatus.php#L95-L96
- [x] Ruby https://github.com/getsentry/sentry-ruby/blob/9bba2ef0a8ef14fa6df8a8a1e5f61e5589375b16/sentry-ruby/lib/sentry/transport/http_transport.rb#L55
- [x] Go https://github.com/getsentry/sentry-go/blob/master/transport.go#L506-L512
- [ ] https://github.com/getsentry/sentry-cocoa/issues/4458
- [ ] Dart ([only considers 200 as successful](https://github.com/getsentry/sentry-dart/blob/8f95e333de1ac9c67a8a928fe77cce146c505818/dart/lib/src/transport/http_transport.dart#L55))
- [ ] Java ([only considers 200 as successful](https://github.com/getsentry/sentry-java/blob/378d12c8be1519ed7caea8bb7db8bcb0ab8275a0/sentry/src/main/java/io/sentry/transport/HttpConnection.java#L273-L275))
- [ ] Rust
- [ ] .NET
- [ ] Native SDK

[cleptric]

@markushi can we make sure this is correctly speced on develop?