`devops::release` issues without a category label

Attention @ogolowinski and @cstasik, The following issues have been identified in the devops::release stage that do not have a category label. These should be applied with urgency so that important issues are not being lost track of.

• #12779 (closed) Review Database Queries for Feature Flags ~"Release", ~"backstage", ~"devops::release", ~"group::progressive delivery"
• #12679 (closed) "Start/Add Merge Train" button should have red background color when the latest pipeline in the merge request has not passed ~"Accepting merge requests", ~"Release", UX, ~"devops::release", ~"devops::release::merge trains", ~"group::progressive delivery"
• #12631 (closed) Environments Dashboard: Explore front-end implementation (mvc) and suggest UX improvements Deliverable, ~"Release", UX, UX debt, ~"devops::release", ~"devops::release::discovery", environments, frontend, ~"group::progressive delivery", usability
• #12149 (closed) Environments > Deploy boards > Improve UI ~"Release", UX, UX debt, ~"devops::release", environments, frontend, ~"group::progressive delivery"
• #11649 (closed) (confidential) ~"(confidential)"