fix(migrate): --from-stack does not retrieved processed template (#29035)

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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: TheRealAmazonKendra

packages/aws-cdk/lib/commands/migrate.ts

@@ -120,7 +120,7 @@ export function readFromPath(inputPath: string): string {
 export async function readFromStack(stackName: string, sdkProvider: SdkProvider, environment: Environment): Promise<string | undefined> {
   const cloudFormation = (await sdkProvider.forEnvironment(environment, Mode.ForReading)).sdk.cloudFormation();
 
-  const stack = await CloudFormationStack.lookup(cloudFormation, stackName);
+  const stack = await CloudFormationStack.lookup(cloudFormation, stackName, true);
   if (stack.stackStatus.isDeploySuccess || stack.stackStatus.isRollbackSuccess) {
     return JSON.stringify(await stack.template());
   } else {