Turn off rp association refresh in nova-next

Set [compute]resource_provider_association_refresh=0 to turn off all
periodic refreshing of the provider cache in the report client.

Note that this probably will have zero effect in the nova-next job
other than making sure that that setting doesn't blow up the world.
Because the job is always doing something, there's never a lull long
enough for the refresh timers to expire anyway, so no periodic
refreshing was happening even before this change.

Change-Id: I072b3fa4847db14e5a3f03c775a377e3514224f1

playbooks/legacy/nova-next/run.yaml

@@ -29,6 +29,12 @@
 
         # Enable TLS between the noVNC proxy & compute nodes; this requires
         # the tls-proxy service to be enabled.
+
+        # Switch off the provider association refresh, which should reduce the
+        # number of placement calls in steady state.
+        # TODO(efried): Due to bug #1802143, nova-cpu.conf gets overwritten
+        # after post-config|$NOVA_CPU_CONF gets effected, so use $NOVA_CONF
+        # instead for now.
         cmd: |
           set -e
           set -x
@@ -38,6 +44,10 @@
           NOVA_CONSOLE_PROXY_COMPUTE_TLS=True
           PLACEMENT_DB_ENABLED=True
 
+          [[post-config|$NOVA_CONF]]
+          [compute]
+          resource_provider_association_refresh = 0
+
           EOF
         executable: /bin/bash
         chdir: '{{ ansible_user_dir }}/workspace'