[release/2025-11B] Add internal/release to official branch prefixes (#6759)

Co-authored-by: Logan Bussell <[email protected]>
Co-authored-by: Matt Thalman <[email protected]>

Author: 3 people

eng/pipelines/variables/core-official.yml

@@ -9,5 +9,8 @@ variables:
 - name: manifest
   value: manifest.json
 
+- name: officialBranchPrefixes
+  value: internal/release/
+
 - name: publishEolAnnotations
   value: true