[td-255] sleep a little bit longer before checking the status of dnodes in the clusters.

tests/script/unique/dnode/alternativeRole.sim

@@ -30,7 +30,7 @@ sql create dnode $hostname2
 system sh/exec.sh -n dnode2 -s start
 sql create dnode $hostname3
 system sh/exec.sh -n dnode3 -s start
-sleep 3000
+sleep 5000
 
 sql show dnodes
 print dnode1 $data5_1