[coverage] Conformance findings: SESSION-010 #883

Surfaced by the multi-language coverage fan-out while conformance-testing these SPEC-IDs against databricks/databricks-sql-python.

Each is committed as an expected-failure (xfail) test in the coverage PR — the test asserts the CORRECT behavior and stays red until this driver is fixed.

• SESSION-010: Thrift session-open auth failure discards the server's detail: an HTTP 401 with "Token has expired" in the body surfaces as a bare RequestError("Error during request to server. "), dropping both the server text and the 401 status, so callers cannot distinguish an expired token from a bad warehouse or a network fault. user_friendly_error_message() appends only header-sourced detail (_extract_error_message_from_headers) and never the HTTP status.

Reference driver PR: databricks/databricks-jdbc#1587
Coverage PR (reproducing xfail tests): https://github.com/databricks/databricks-driver-test/pull/974