Remove usage of LegacyEngineFacade

This helper class of oslo.db was deprecated long time ago

Change-Id: Ibdc6e3aa5fa3b729a95356f27ee9f6dab1eef3c7

rally/common/db/api.py

@@ -47,7 +47,7 @@ import time
 
 from oslo_db import exception as db_exc
 from oslo_db import options as db_options
-from oslo_db.sqlalchemy import session as db_session
+from oslo_db.sqlalchemy import enginefacade
 import sqlalchemy as sa
 import sqlalchemy.orm   # noqa
 
@@ -71,14 +71,19 @@ def _create_facade_lazily():
     global _FACADE
 
     if _FACADE is None:
-        _FACADE = db_session.EngineFacade.from_config(CONF)
+        ctx = enginefacade.transaction_context()
+        ctx.configure(
+            sqlite_fk=False,
+            __autocommit=False,
+            expire_on_commit=False
+        )
+        _FACADE = ctx
 
     return _FACADE
 
 
 def get_engine():
-    facade = _create_facade_lazily()
-    return facade.get_engine()
+    return _create_facade_lazily().writer.get_engine()
 
 
 def get_session():

tox.ini

@@ -143,7 +143,6 @@ commands = \
 [pytest]
 filterwarnings =
     error
-    ignore:.*EngineFacade is deprecated; please use oslo_db.sqlalchemy.enginefacade*:
     # Introduced with oslo.db-12.1.0
     ignore:.*Support for the MySQL NDB Cluster storage engine has been deprecated and will be removed in a future release.:DeprecationWarning:
     # Introuduced with SQLAlchemy-1.4.46, can be removed when rally supports SQLAlchemy>=2.0.0