revert: "chore(cdk): boostrap template uses deprecated AccessControl property" (#27939)

Reverts #27764

Author: colifran

packages/aws-cdk/lib/api/bootstrap/bootstrap-template.yaml

@@ -182,6 +182,7 @@ Resources:
           - HasCustomFileAssetsBucketName
           - Fn::Sub: "${FileAssetsBucketName}"
           - Fn::Sub: cdk-${Qualifier}-assets-${AWS::AccountId}-${AWS::Region}
+      AccessControl: Private
       BucketEncryption:
         ServerSideEncryptionConfiguration:
           - ServerSideEncryptionByDefault: