fix(codepipeline): default cross-region S3 buckets allow public access (#17722)

The cross region S3 buckets that are created should have block public access by default.

Fixes #16411

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

Author: david-richer-adsk

packages/@aws-cdk/aws-codepipeline/lib/private/cross-region-support-stack.ts

@@ -77,6 +77,7 @@ export class CrossRegionSupportConstruct extends Construct {
       bucketName: cdk.PhysicalName.GENERATE_IF_NEEDED,
       encryption: encryptionAlias ? s3.BucketEncryption.KMS : s3.BucketEncryption.KMS_MANAGED,
       encryptionKey: encryptionAlias,
+      blockPublicAccess: s3.BlockPublicAccess.BLOCK_ALL,
     });
   }
 }

packages/@aws-cdk/aws-codepipeline/test/cross-env.test.ts

@@ -129,7 +129,14 @@ describe.each([
 
         // THEN
         expect(supportStack).not.toHaveResource('AWS::KMS::Key');
-        expect(supportStack).toHaveResource('AWS::S3::Bucket');
+        expect(supportStack).toHaveResourceLike('AWS::S3::Bucket', {
+          PublicAccessBlockConfiguration: {
+            BlockPublicAcls: true,
+            BlockPublicPolicy: true,
+            IgnorePublicAcls: true,
+            RestrictPublicBuckets: true,
+          },
+        });
       });
 
       test('when twiddling another stack', () => {