Deprecate and remove older MR widget telemetry events
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As a follow-up to [this discussion on the MR to remove these events from our new reporting code infrastructure](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/114018#note_1308013166), this begins the [remove a metric](https://docs.gitlab.com/ee/development/service_ping/metrics_lifecycle.html#remove-a-metric) process to deprecate and remove:
- `i_testing_code_quality_widget_total`
- `i_testing_terraform_widget_total`
- `i_testing_issues_widget_total`
- `i_testing_summary_widget_total`
- `i_testing_metrics_report_widget_total`
- `i_testing_web_performance_widget_total`
- `i_testing_license_compliance_widget_total`
- `i_testing_load_performance_widget_total`
- `i_testing_status_checks_widget`
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