Enable skip_default_scope_for_events FF by default

What does this MR do and why?

This MR enables the skip_default_scope_for_events feature flag by default. No observed issues so far since the flag was enabled on PRD: #372464 (closed)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #372464 (closed)