Use env again, only run 'Check for changes' on push

.github/workflows/sync-backport-changelog.yml

@@ -20,22 +20,17 @@ jobs:
             )
         steps:
             - name: Checkout
-              if: github.event_name == 'push'
               uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
               with:
                   fetch-depth: 2 # Fetch the last two commits to compare changes
             - name: Check for changes in backport-changelog
-              id: check-for-changes
+              if: github.event_name == 'push'
               run: |
-                  git diff --quiet HEAD^ HEAD -- backport-changelog || echo "HAS_CHANGES=1" >> "$GITHUB_OUTPUT"
+                  if git diff --quiet HEAD^ HEAD -- backport-changelog; then
+                      echo "skip_sync=true" >> "$GITHUB_ENV"
+                  fi
             - name: Sync Issue
-              if: >
-                  steps.check-for-changes.outputs.HAS_CHANGES ||
-                  (
-                      github.event_name == 'issues' &&
-                      github.event.action == 'labeled' &&
-                      github.event.label.name == '🤖 Sync Backport Changelog'
-                  )
+              if: ${{ ! env.skip_sync }}
               uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
               with:
                   script: |