Remove old CI/CD Analytics code

What does this MR do and why?

This MR removes legacy CI/CD Analytics code that has been replaced by the new Analytics Dashboards implementation. The cleanup focuses on deleting old DORA metrics chart components and their associated utilities that are no longer needed.

Changes summary

Deleted Vue components:

• change_failure_rate_charts.vue - Old change failure rate visualization
• deployment_frequency_charts.vue - Old deployment frequency visualization
• lead_time_charts.vue - Old lead time for changes visualization
• time_to_restore_service_charts.vue - Old time to restore service visualization
• dora_chart_header.vue - Shared header component for old charts

Deleted JavaScript files:

• util.js - Chart data transformation utilities
• Static data files for each metric (change_failure_rate.js, deployment_frequency.js, lead_time.js, time_to_restore_service.js, shared.js)

Deleted test files:

• All corresponding spec files for the deleted components
• Snapshot files for component tests

Updated:

• locale/gitlab.pot - Removed unused translation strings related to the old charts

This is a pure deletion/cleanup MR with no functional changes to the new Analytics Dashboards implementation.

References

Related to #542910 (closed)

Screenshots or screen recordings

No visual changes

How to set up and validate locally

1. Verify that the new Analytics Dashboards DORA metrics functionality still works as expected
2. Confirm that no references to the deleted files remain in the codebase

MR acceptance checklist

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