[v8] Remove public APIs around Hub class

[Lms24]

It seems we forgot to actually deprecate and remove the Hub class. For v8 and onwards, there's no need to publicly keep the class around

### Public API - (breaking) changes
- [ ] https://github.com/getsentry/sentry-javascript/pull/11528
- [ ] https://github.com/getsentry/sentry-javascript/pull/11530
- [ ] https://github.com/getsentry/sentry-javascript/pull/11539
- [ ] https://github.com/getsentry/sentry-javascript/pull/11536
- [ ] https://github.com/getsentry/sentry-javascript/pull/11560
- [ ] https://github.com/getsentry/sentry-javascript/pull/11565
- [ ] https://github.com/getsentry/sentry-javascript/pull/11581

### Internal Changes
- [x] Rewrite `getCurrentHub` to return a simple "aliasing" object instead satisfying `HubInterface`
- [ ] https://github.com/getsentry/sentry-javascript/pull/11630