Run nova-next with n-sch in threading mode

Depends-On: https://review.opendev.org/c/openstack/devstack/+/948436

Change-Id: I36c68740fae3e3a9bd3286a1b66d86fd3341aff5
Signed-off-by: Balazs Gibizer <gibi@redhat.com>

.zuul.yaml

@@ -427,6 +427,11 @@
             scheduler:
               # Added in Train.
               query_placement_for_image_type_support: True
+            DEFAULT:
+              # Added in Flamingo. Ensures that thread statistics is logged
+              # each time a task is submitted to the executor so that web
+              # can troubleshoot hanging threads easier.
+              thread_pool_statistic_period: 0
           "/$NEUTRON_CORE_PLUGIN_CONF":
             # Needed for QoS port heal allocation testing.
             ovs:
@@ -469,6 +474,7 @@
         # Temporarly disabled due to
         # https://bugs.launchpad.net/nova/+bug/2110545
         NOVA_COMPILE_MDEV_SAMPLES: False
+        'SYSTEMD_ENV_VARS["n-sch"]': OS_NOVA_DISABLE_EVENTLET_PATCHING=true
       devstack_services:
         # Disable OVN services
         br-ex-tcpdump: false