profiling-node should store `profile_id` on span rather than profile context

### Description

Currently `@sentry/profiling-node` stores the `profile_id` on the isolated context:
https://github.com/getsentry/sentry-javascript/blob/ec02f84fc6597e73bbc1c6d905da7b12b15dbc07/packages/profiling-node/src/integration.ts#L87

This means the profile cannot be found if there are multiple versions of `@sentry/core` in the dependencies.

Instead can we store the `profile_id` on the span? There's already a property for this:
https://github.com/getsentry/sentry-javascript/blob/bfe7bfa53270fc6f173e49f79177d367f1c78639/packages/core/src/types-hoist/span.ts#L49

Then the integration wouldn't rely on updating any scope. In the `beforeEnvelope` hook we just go through the spans until we find a `profile_id`?