Change cluster auto-down-after-unreachable-after
setting to 30s to go along with the controller
change for BUG 4037 in
https://git.opendaylight.org/gerrit/#/c/27852/.
Change-Id: If49bbd43c29f3ec1b830e9f341b79707638eeab0 Signed-off-by: Gary Wu <Gary.Wu1@huawei.com>