fix(spans): Span V2 nullable fields

[jjbayer]

Since kafka spans are now a superset of Span V2 & support _meta annotations, almost any field can be null. Only meta fields like organization_id are guaranteed to exist.

[github-actions]

versions in use:

The following repositories use one of the schemas you are editing. It is recommended to roll out schema changes in small PRs, meaning that if those used versions lag behind the latest, it is probably best to update those services before rolling out your change.

latest version: 2.1.7

benign changes

schemas/ingest-spans.v1.schema.json

• {"path": ".is_remote", "change": {"TypeAdd": {"added": "null"}}}
  

• {"path": ".links", "change": {"TypeAdd": {"added": "null"}}}
  

• {"path": ".name", "change": {"TypeAdd": {"added": "null"}}}
  

• {"path": ".span_id", "change": {"TypeAdd": {"added": "null"}}}
  

✅ This PR should be safe to roll out to consumers first. Make sure to bump
the library in the following repos first:

...then in the other repos:

getsentry/sentry

Take a look at the README for how to release a new version of sentry-kafka-schemas.