chore: update message in GHA lock conversations (aws#30942)

### Issue # (if applicable)

Fix the misleading message in aws#30941

### Reason for this change

Update message left by GHA

### Description of changes

Since we lock conversations, we should update the message to be more accurate.

### Description of how you validated changes

Tested in private fork with GHA.

### 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*

.github/workflows/lock-issue-pr-with-message.yml

@@ -19,13 +19,12 @@ jobs:
           message: |
             Comments on closed issues and PRs are hard for our team to see. 
             If you need help, please open a new issue that references this one.
-            If you wish to keep having a conversation with other community members under this issue feel free to do so.
   lock:
     permissions:
       pull-requests: write
       issues: write
     runs-on: ubuntu-latest
-    needs: auto_comment
+    needs: auto_comment # only run after comment is complete
     steps:
       - name: Lock closed issue or PR
         run: |