Use new schema version when sending feature_enabled_by_namespace_ids

What does this MR do and why?

Gist: We're sending all snowplow events from the backed using the wrong schema version, so all the events are erroring.

A new field feature_enabled_by_namespace_ids was added to the snowplow standard context, but the rails app wasn’t updated to reference the new schema:

• https://gitlab.com/gitlab-org/iglu/-/merge_requests/112+
• Track namespaces that empowered a user to use a... (!148463 - merged)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Counts of total bad events over 15 minutes periods:

Count of bad events over the last 24 hours, grouped by error message: