Disable heartbeat_in_pthread by default

The default value for heartbeat_in_pthread has been reverted in
oslo.messaging to False [1] and backported back to Yoga.

At the moment this setting brings intermittent issues during live
migrations of instances and some other operations. So makes sense
to align it with default value.

[1] https://review.opendev.org/c/openstack/oslo.messaging/+/852251

Change-Id: I5601726095ff19620de2d87220efad191cf7cb6d

defaults/main.yml

@@ -133,7 +133,7 @@ nova_cell_force_update: False
 ## Oslo Messaging
 
 # RabbitMQ
-nova_oslomsg_heartbeat_in_pthread: "{{ oslomsg_heartbeat_in_pthread | default(_nova_oslomsg_heartbeat_in_pthread) }}"
+nova_oslomsg_heartbeat_in_pthread: "{{ oslomsg_heartbeat_in_pthread | default(False) }}"
 
 # RPC
 nova_oslomsg_rpc_host_group: "{{ oslomsg_rpc_host_group | default('rabbitmq_all') }}"

releasenotes/notes/heartbeat_in_pthread_to_false-4bde8fca9a332805.yaml

@@ -0,0 +1,8 @@
+---
+other:
+  - |
+    In order to align with oslo.messaging `reverted default <https://review.opendev.org/c/openstack/oslo.messaging/+/852251>`_
+    of ``heartbeat_in_pthread`` value we remove own logic of
+    handling the value based on host groups.
+    You still can use ``oslomsg_heartbeat_in_pthread`` or specific role
+    variables to alter the behaviour.

vars/main.yml

@@ -159,8 +159,6 @@ _qemu_default_conf_dict: |-
 
 _nova_qemu_conf: "{{ _qemu_default_conf_dict | combine(qemu_conf_dict) }}"
 
-_nova_oslomsg_heartbeat_in_pthread: "{{ (nova_services['nova-compute']['group'] in group_names) | ternary(False, True) }}"
-
 _nova_cache_backend_map:
   dogpile:
     - oslo_cache.memcache_pool