Update links in development docs

doc/.vale/gitlab/spelling-exceptions.txt

doc/administration/feature_flags.md

doc/development/code_review.md

doc/development/database/index.md

doc/development/documentation/feature_flags.md

doc/development/documentation/testing.md

doc/development/fe_guide/graphql.md

doc/development/fe_guide/style/vue.md

doc/development/feature_flags/controls.md

doc/development/integrations/secure_partner_integration.md

doc/development/merge_request_performance_guidelines.md

doc/development/new_fe_guide/tips.md

doc/development/testing_guide/frontend_testing.md