Remove total duration from analytics page

What does this MR do?

This removes the "Total duration" statistic from the frontend of the Project -> Analytics -> CI/CD page

The changes are behind the graphql_pipeline_analytics feature flag

#293901 (closed)

The backend MR that removes this field is here !50093 (merged)

Screenshots (strongly suggested)

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content