Remove unused BRANCH_NAME variable from validation step

Co-authored-by: jmiller-moko <230051081+jmiller-moko@users.noreply.github.com>

.github/workflows/version_branch.yml

@@ -300,8 +300,6 @@ jobs:
           #
           # Rule: If a version exists in a higher priority branch, 
           # do not allow creating it in a lower priority branch
-
-          BRANCH_NAME="${BRANCH_PREFIX}${NEW_VERSION}"
           
           echo "[INFO] Checking version hierarchy for: ${NEW_VERSION}"
           echo "[INFO] Current branch prefix: ${BRANCH_PREFIX}"