chore: fix enum updater static mapping PR process (#34188)

### Reason for this change

There're some issues in the enum updater workflow.
- When checking if there're specific file changed, the directory is not right
- typo in Github PR creating command.

### Checklist
- [ ] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: xazhao

.github/workflows/enum-auto-updater.yml

@@ -33,6 +33,7 @@ jobs:
       - name: Check for changes
         id: static-mapping-check
         run: |
+          cd tools/@aws-cdk/enum-updater
           if [[ -n "$(git status --porcelain ./lib/static-enum-mapping.json)" ]]; then
             echo "changes=true" >> $GITHUB_OUTPUT
           else
@@ -42,6 +43,7 @@ jobs:
       - name: Create PR for static mapping changes
         if: steps.static-mapping-check.outputs.changes == 'true'
         run: |
+          cd tools/@aws-cdk/enum-updater
           git config --global user.name 'aws-cdk-automation'
           git config --global user.email '[email protected]'
 
@@ -56,8 +58,10 @@ jobs:
           gh pr create --title "chore: update enum static mapping" \
            --body "This PR updates the CDK enum mapping file." \
            --base main \
-           --head "$branchName"
+           --head "$branchName" \
            --label "contribution/core,pr-linter/exempt-integ-test,pr-linter/exempt-readme,pr-linter/exempt-test"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Identify Missing Values and Apply Code Changes
         run: |