[Regression] Show exception details when using Development mode

Starting with runtime [v2.0.12134](https://github.com/Azure/azure-functions-host/releases/tag/v2.0.12134),
HttpTrigger 500 response does not include exception stack trace even though AZURE_FUNCTIONS_ENVIRONMENT is set to "development"

This is useful for testing exceptions without parsing logs

Reproduce an HttpTrigger 500 response with AZURE_FUNCTIONS_ENVIRONMENT set to "development", comparing runtime v2.0.12134 with an earlier version. Trace how the host handles exception responses in Development mode; done means the response includes the exception stack trace without requiring log parsing.

Written by the indexing model from the issue text.