Enable graphql_code_quality_full_report by default

What does this MR do and why?

In support of moving Investigation: Code Quality performance with mu... (#358759 - closed) forward and as part of [Feature flag] Rollout of `graphql_code_quality... (#340525 - closed) this MR enables the graphql_code_quality_full_report Feature Flag by default.

Note: The flag has been on for the gitlab-org/gitlab project for roughly a year.

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