fix(ecr): Generate valid CloudFormation for imageScanOnPush (#13420)

fix #13418: Update ECR construct to generate valid CloudFormation when enabling `imageScanOnPush`


----

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

Author: cplee

packages/@aws-cdk/aws-ecr/lib/repository.ts

@@ -450,7 +450,7 @@ export class Repository extends RepositoryBase {
       repositoryPolicyText: Lazy.any({ produce: () => this.policyDocument }),
       lifecyclePolicy: Lazy.any({ produce: () => this.renderLifecyclePolicy() }),
       imageScanningConfiguration: !props.imageScanOnPush ? undefined : {
-        scanOnPush: true,
+        ScanOnPush: true,
       },
     });
 

packages/@aws-cdk/aws-ecr/test/integ.imagescan.expected.json

@@ -4,7 +4,7 @@
       "Type": "AWS::ECR::Repository",
       "Properties": {
         "ImageScanningConfiguration": {
-          "scanOnPush": true
+          "ScanOnPush": true
         }
       },
       "UpdateReplacePolicy": "Delete",
@@ -87,4 +87,4 @@
       }
     }
   }
-}
+}

packages/@aws-cdk/aws-ecr/test/test.repository.ts

@@ -38,7 +38,7 @@ export = {
     // THEN
     expect(stack).to(haveResource('AWS::ECR::Repository', {
       ImageScanningConfiguration: {
-        scanOnPush: true,
+        ScanOnPush: true,
       },
     }));
     test.done();