Sync rally config from Neutron.

We intend to run the same rally config used for the main Neutron repo.
Sync with changes made in Neutron.

Change-Id: Ib3ba87f6fd520f9ffc1c8ea304d6e6eb1f1b806a
Signed-off-by: Russell Bryant <rbryant@redhat.com>

rally-jobs/ovn.yaml

@@ -73,7 +73,7 @@
       args:
         network_create_args:
         port_create_args:
-        ports_per_network: 100
+        ports_per_network: 50
       runner:
         type: "constant"
         times: 8
@@ -130,7 +130,7 @@
             name: "_subnet_updated"
       runner:
         type: "constant"
-        times: 400
+        times: 100
         concurrency: 20
       context:
         users:
@@ -305,4 +305,3 @@
       sla:
         failure_rate:
           max: 0
-