Remove QA test template (qa-customizable-media-test) once customizableMedia flag is enabled for all users

[linear]

Tech Debt

When the customizableMedia feature flag was introduced, a QA-only test template with the slug prefix qa-customizable-media-test was added to the templates library. To prevent it from appearing in the public /templates page, a slug filter was added that hides it when the flag is disabled.

Once the customizableMedia flag is fully rolled out to all users, this filter will no longer apply and the QA test template will become visible to all users.

Action Required

• Delete the QA test template (qa-customizable-media-test) from the templates library in the JFP team.
• Remove the QA_ONLY_TEMPLATE_SLUG_PREFIX constant and the associated filter logic from TemplateSections.tsx.
• Remove the related test coverage for this filter.

Relevant Code

libs/journeys/ui/src/components/TemplateSections/TemplateSections.tsx

[linear]

ENG-3584