test: cases for alter stb

tests/script/tsim/stable/alter_count.sim

@@ -248,8 +248,9 @@ endi
 
 print ============== step18
 system sh/exec.sh -n dnode1 -s stop -x SIGINT
+sleep 3000
 system sh/exec.sh -n dnode1 -s start
-sql connect
+sleep 3000
 
 #sql select count(g) from tb
 #if $data00 != 12 then

tests/script/tsim/stable/alter_insert1.sim

@@ -936,8 +936,9 @@ endi
 print ======== step9
 
 system sh/exec.sh -n dnode1 -s stop -x SIGINT
+sleep 3000
 system sh/exec.sh -n dnode1 -s start
-sql connect
+sleep 3000
 
 sql select * from tb order by ts asc
 if $rows != 8 then

tests/script/tsim/stable/alter_insert2.sim

@@ -604,8 +604,9 @@ sql_error alter table tb drop column a
 
 print ======== step9
 system sh/exec.sh -n dnode1 -s stop -x SIGINT
+sleep 3000
 system sh/exec.sh -n dnode1 -s start
-sql connect
+sleep 3000
 
 sql select * from tb order by ts desc
 if $rows != 7 then