Fix compatibility with oslo.db 12.1.0

oslo.db 12.1.0 has changed the default value for the 'autocommit'
parameter of 'LegacyEngineFacade' from 'True' to 'False'. This is a
necessary step to ensure compatibility with SQLAlchemy 2.0. However, we
are currently relying on the autocommit behavior and need changes to
explicitly manage sessions. Until that happens, we need to override the
default.

Also squashed change: [CI] move queue setting to project level

Jobs are currently not running. Fix as described in [1][2]

[1] https://lists.opendev.org/pipermail/service-announce/2022-September/000044.html
[2] https://lists.zuul-ci.org/pipermail/zuul-discuss/2022-May/001801.html

Story: 2010296
Co-Authored-By: Stephen Finucane <stephenfin@redhat.com>
Co-Authored-By: Jake Yip <jake.yip@ardc.edu.au>
Change-Id: I625500d9e6670a429c70a0f6d582d0865ce78fd1

.zuul.yaml

@@ -50,6 +50,7 @@
     timeout: 2400
 
 - project:
+    queue: magnum
     templates:
       - openstack-cover-jobs
       - openstack-python3-zed-jobs
@@ -61,7 +62,6 @@
         - magnum-tempest-plugin-tests-api
         - magnum-container-build
     gate:
-      queue: magnum
       jobs:
         - magnum-tempest-plugin-tests-api
     post:

magnum/db/sqlalchemy/api.py

@@ -48,7 +48,9 @@ _FACADE = None
 def _create_facade_lazily():
     global _FACADE
     if _FACADE is None:
-        _FACADE = db_session.EngineFacade.from_config(CONF)
+        # FIXME(karolinku): autocommit=True it's not compatible with
+        # SQLAlchemy 2.0, and will be removed in future
+        _FACADE = db_session.EngineFacade.from_config(CONF, autocommit=True)
         if profiler_sqlalchemy:
             if CONF.profiler.enabled and CONF.profiler.trace_sqlalchemy:
                 profiler_sqlalchemy.add_tracing(sa, _FACADE.get_engine(), "db")