Remove `Hub` related code

POTel PRs: [https://github.com/getsentry/sentry-python/pull/3446](https://github.com/getsentry/sentry-python/pull/3446) [https://github.com/getsentry/sentry-python/pull/3412](https://github.com/getsentry/sentry-python/pull/3412)