Refine LRO to give more robust mock response

1. Create different polling URL for different LRO according to swagger LRO definition.
2. Make the whole LRO mock process more similar to real traffic.

The issue names LRO mocking and Swagger LRO definitions but provides no files or tests. Start by locating the existing LRO mock entry point and comparing its polling URLs and traffic with the relevant definitions. Done means different polling URLs for each LRO and mock behavior closer to real traffic.

Written by the indexing model from the issue text.