fix(core): DefaultStackSynthesizer bucket prefix missing for template…

… assets (#11855)

Related to #10710, #11327 @rix0rrr 

Adding bucketPrefix to "stackTemplateAssetObjectUrl"

----

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

packages/@aws-cdk/core/lib/stack-synthesizers/default-synthesizer.ts

@@ -442,7 +442,7 @@ export class DefaultStackSynthesizer extends StackSynthesizer {
     //
     // Instead, we'll have a protocol with the CLI that we put an 's3://.../...' URL here, and the CLI
     // is going to resolve it to the correct 'https://.../' URL before it gives it to CloudFormation.
-    return `s3://${this.bucketName}/${sourceHash}`;
+    return `s3://${this.bucketName}/${this.bucketPrefix}${sourceHash}`;
   }
 
   /**

packages/@aws-cdk/core/test/stack-synthesis/new-style-synthesis.test.ts

@@ -243,6 +243,9 @@ nodeunitShim({
     // WHEN
     const asm = myapp.synth();
 
+    // THEN -- the S3 url is advertised on the stack artifact
+    const stackArtifact = asm.getStackArtifact('mystack-bucketPrefix');
+
     // THEN - we have an asset manifest with both assets and the stack template in there
     const manifest = readAssetManifest(asm);
 
@@ -254,6 +257,10 @@ nodeunitShim({
       assumeRoleExternalId: 'file-external-id',
     });
 
+    const templateHash = last(stackArtifact.stackTemplateAssetObjectUrl?.split('/'));
+
+    test.equals(stackArtifact.stackTemplateAssetObjectUrl, `s3://file-asset-bucket/000000000000/${templateHash}`);
+
     test.done();
   },