chore(cdk): boostrap template uses deprecated AccessControl property (#27764)

Use of AccessControl is deprecated — see
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-s3-bucket.html#cfn-s3-bucket-accesscontrol

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

Author: scarytom

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

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