[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
4 files changed