Enable explain code in web ui for self-managed

We have found that: explain code button is using service to check authorization in those two places: https://gitlab.com/gitlab-org/gitlab/-/blob/e97034c5fe476260771519a5ee75e963b3b389ce/ee/app/helpers/ee/blob_helper.rb#L10 https://gitlab.com/gitlab-org/gitlab/-/blob/e97034c5fe476260771519a5ee75e963b3b389ce/ee/app/helpers/ee/tree_helper.rb#L14 so to show this button, we are using the “explain code service”, that is however not used to actually explain the code

next steps: it seems that the functionality that opens chat for explanation was implemented and enabled: a0791aa8 And removed: !143217 (merged) The feature flag was removed on frontend, but not on backend I believe we need to: Clean up the feature flag Replace explain_code_available logic with the one that just checks that duo chat is accessible (please correct me if I’m wrong) Clean up ExplainCodeService