[FF] active_context_code_event_mark_repository_ready -- rollout

Summary

This issue is to roll out the feature on production, that is currently behind the active_context_code_event_mark_repository_ready feature flag.

Owners

• Most appropriate Slack channel to reach out to: #g_global_search
• Best individual to reach out to: @maddievn

JTBD

• Remove FF definition
• Remove code references to FF
• Remove spec references to FF

https://docs.gitlab.com/development/event_store/#register-the-subscriber-to-the-event