[ovn] Increase mac table size for provider bridge

Default mac table size (2048 for OVS<2.10) isn't enough for
busy environments and can lead to its overflow and as a result
of the consuming 100% CPU by ovs-vswitchd process.

Change-Id: I172e9adeba641bb72544f28f08afc8f67aa63261
Closes-Bug: PROD-27400
diff --git a/tests/pillar/compute_ovn.sls b/tests/pillar/compute_ovn.sls
index f3fbaf1..8ced50d 100644
--- a/tests/pillar/compute_ovn.sls
+++ b/tests/pillar/compute_ovn.sls
@@ -8,6 +8,7 @@
     backend:
       engine: ovn
       ovsdb_connection: tcp:127.0.0.1:6640
+      mac_table_size: 8192
     metadata:
       enabled: true
       ovsdb_server_iface: ptcp:6640:127.0.0.1