[system test][kv unix] could not stop couchbase server unless force kill beam.smp

nstall couchbase server 3.0.0-1089 on 8 nodes
1:172.23.107.195
2:172.23.107.196
3:172.23.107.197
4:172.23.107.199
5:172.23.107.200
6:172.23.107.202
7:172.23.107.201

8:172.23.107.203

Create a cluster of 7 nodes
Create 2 buckets: default and sasl-2 (no view)
Load 25+ M items to each bucket to bring down active resident ratio down to 80%
Do update, expired and delete on both buckets in 3 hours.
Then add node 203 to cluster. Rebalance hang when rebalance second bucket with low priority setting. MB-11870
Shutdown cluster to uninstall couchbase server. Could not shutdown coucbase server.
Reboot all servers.
Then uninstall couchbase server. Uninstall failed due to could not stop couchbase server.
Manually stop couchbase server on node 195 /etc/init.d/couchbase-server stop (failed)
Only using command line killall -9 beam.smp to force stop couchbase server