chore(cli-integ): migrate tests can fail because they don't bootstrap (#32714)

CDK Migrate tests rely on other tests having bootstrapped their target regions already. That fails if they run first.

Add bootstrapping commands to these tests as well.

----

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

Author: rix0rrr

packages/@aws-cdk-testing/cli-integ/lib/with-cdk-app.ts

@@ -117,6 +117,8 @@ export function withCdkMigrateApp<A extends TestContext>(language: string, block
       context.randomString,
     );
 
+    await ensureBootstrapped(fixture);
+
     await fixture.cdkMigrate(language, stackName);
 
     const testFixture = new TestFixture(