addons: bridge: down: when ifreload_down_changed=1: purge bridge and upper devices cache
On ifreload (down ops) we need to purge the cache entry of the bridge and its upper devices
to avoid stale values in our cache.
ifup this config, then remove bridge-vids 20, ifreload: since the bridge is removed because
of ifreload_down_changed=1, we need torecreate the vlan bridge.10 and it's configuration, the
cache is stale. We need to clear it to remove the ip 10.10.10.10/32.