Adjust redis-cli --cluster create arity from -2 to -1 (#12892)

When arity is -2, it allows us to input two nodes, but returns:
```
*** ERROR: Invalid configuration for cluster creation.
*** Redis Cluster requires at least 3 master nodes.
*** This is not possible with 2 nodes and 0 replicas per node.
*** At least 3 nodes are required.
```

When we input one node, it return:
```
[ERR] Wrong number of arguments for specified --cluster sub command
```

Strictly speaking -2 should also be rejected, because redis-cli
requires at least three nodes. However, the error message was not
very friendly, so decided to change it arity -1.

This closes #12891.

src/redis-cli.c

@@ -3765,7 +3765,7 @@ typedef struct clusterManagerCommandDef {
 } clusterManagerCommandDef;
 
 clusterManagerCommandDef clusterManagerCommands[] = {
-    {"create", clusterManagerCommandCreate, -2, "host1:port1 ... hostN:portN",
+    {"create", clusterManagerCommandCreate, -1, "host1:port1 ... hostN:portN",
      "replicas <arg>"},
     {"check", clusterManagerCommandCheck, -1, "<host:port> or <host> <port> - separated by either colon or space",
      "search-multiple-owners"},