Remove usage_data_i_testing_test_case_parsed feature flag

Changelog: added

config/feature_flags/development/usage_data_i_testing_test_case_parsed.yml

----
-name: usage_data_i_testing_test_case_parsed
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41918
-rollout_issue_url: 
-milestone: '13.5'
-type: development
-group: group::testing
-default_enabled: true

lib/gitlab/usage_data_counters/known_events/common.yml

@@ -149,7 +149,6 @@
   category: testing
   redis_slot: testing
   aggregation: weekly
-  feature_flag: usage_data_i_testing_test_case_parsed
 - name: i_testing_metrics_report_widget_total
   category: testing
   redis_slot: testing