use 'ci-auto-merge' env for workflow that auto-merges PR

Author: swibi-ttd

.github/workflows/release-docker-image.yaml

@@ -50,6 +50,7 @@ jobs:
       release_type: ${{ inputs.release_type }}
       vulnerability_severity: ${{ inputs.vulnerability_severity }}
       java_version: 21
+      merge_environment: ${{ github.ref_protected && 'ci-auto-merge' || '' }}
     secrets: inherit
 
   e2e-test: