End-to-end tests: Add CDK feature flags

[madeline-k]

Currently, the end-to-end tests create a CDK app without any feature flags set.

We should update the tests/end-to-end/app-boilerplate-files/ for each language to include a context file with the latest default feature flags of a new CDK app. This should be a very simple matter of just adding the file, because the tests already use all files in each boilerplate directory when creating CDK apps.