Revert "Remove usage of LegacyEngineFacade"

Temporary reverts commit 01018c1b1e.
This change will be added back as a part of bigger commit

Change-Id: I45600b817cada2266341afa0ac9dbfec6ce7e62e

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

tox.ini

@@ -137,6 +137,7 @@ 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:
     # Introduced with SQLAlchemy-1.4.46, can be removed when rally supports SQLAlchemy>=2.0.0