pd-ctl should return non-zero exit code on error

[cjc7373]

Enhancement Task

In some automated scripts, it is hard to tell if a command succeeds because pd-ctl returns 0 on error.

For example:

[root@tidb-cluster-tikv-0 /]# /pd-ctl -u "$PD_ADDRESS" store delete addr ""
address not found: 
[root@tidb-cluster-tikv-0 /]# echo $?
0

[rleungx]

PTAL @JackL9u