validate-apis: Fix branch condition

Author: pquentin

.github/workflows/validate-apis.yml

@@ -71,12 +71,11 @@ jobs:
       - name: Download artifacts
         working-directory: ./clients-flight-recorder
         run: |
-          if [[ -n "${GITHUB_BASE_REF+x}" ]]; then
+          if [[ -n "${GITHUB_BASE_REF:-}" ]]; then
             branch=$GITHUB_BASE_REF
           else
             branch=$GITHUB_REF_NAME
           fi
-          env
           echo "Using branch: $branch"
           node scripts/upload-recording/download.js --branch $branch --git
           node scripts/clone-elasticsearch/index.js --branch $branch