Remove code quality usage feature flag

What does this MR do?

Related to #332396 (closed)

Remove the feature flag :usage_data_i_testing_full_code_quality_report_total as it is no longer needed.

Screenshots or Screencasts (strongly suggested)

How to setup and validate locally (strongly suggested)

1. Create a project with a Code Quality report and run a pipeline
2. View the completed pipeline details page
3. Open network requests tab in dev tools
4. Click on the Code Quality tab
5. Verify that a POST request was sent to increment_unique_users and that it returned 200.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.