Merge branch '426246-explai-code-duo-chat' into 'master'

Use Duo Chat for explain code feature

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143217



Merged-by: Denys Mishunov <dmishunov@gitlab.com>
Approved-by: Rudy Crespo <rcrespo@gitlab.com>
Approved-by: Julia Miocene <jmiocene@gitlab.com>
Approved-by: Suzanne Selhorn <sselhorn@gitlab.com>
Reviewed-by: Jacques Erasmus <jerasmus@gitlab.com>
Reviewed-by: Denys Mishunov <dmishunov@gitlab.com>
Reviewed-by: Marcin Sedlak-Jakubowski <msedlakjakubowski@gitlab.com>
Reviewed-by: Rudy Crespo <rcrespo@gitlab.com>
Co-authored-by: Jacques <jerasmus@gitlab.com>