ci: let wrangler auto-detect branch name from GitHub Actions env vars

Wrangler now reads GITHUB_HEAD_REF/GITHUB_REF_NAME natively
(cloudflare/workers-sdk#12983), so we no longer need to manually
derive and pass --name to the preview deploy command.

Author: maxwellpeterson

.github/workflows/preview.yml

@@ -38,8 +38,7 @@ jobs:
           VITE_MAPBOX_TOKEN: ${{ secrets.VITE_MAPBOX_TOKEN }}
         run: |
           set +e
-          preview_name=$(echo "${{ github.head_ref }}" | cut -c1-53)
-          output=$(npm run deploy:preview -- --name "$preview_name" 2>&1)
+          output=$(npm run deploy:preview 2>&1)
           exit_code=$?
           set -e
           echo "$output"