This internal refactor lets automated browser and RPC tests share the same test data connection, making test setup and result checks simpler and more reliable. It affects testing infrastructure and related module tests, with no expected direct impact on day-to-day user workflows.

This allows rpc requests in `HttpCase` to use the cursor `self.cr`, which is now shared between the Python test and the rpc requests.  This simplifies code to prepare a JS test, and code to check the result of a JS tour.