chore: limit workflow to run by aws-cdk-automation only (#33893)

### Issue # (if applicable)

N/A

### Reason for this change

Only allow the workflow to run by aws-cdk-automation.

### Description of changes

Limit the github author to be aws-cdk-automation.

### Describe any new or updated permissions being added

N/A

### Description of how you validated changes

N/A

### 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: GavinZZ

.github/workflows/analytics-metadata-updater.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   update-analytics-metadata:
-    if: github.repository == 'aws/aws-cdk'
+    if: github.repository == 'aws/aws-cdk' && github.actor == 'aws-cdk-automation'
     runs-on: ubuntu-latest
     permissions:
       contents: write

.github/workflows/lambda-runtime-tests.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   update-lambda-tests:
-    if: github.repository == 'aws/aws-cdk'
+    if: github.repository == 'aws/aws-cdk' && github.actor == 'aws-cdk-automation'
     runs-on: ubuntu-latest
     permissions:
       contents: write