CFG: Add @kind graph to Cfg.ql, and remove labels from ordinary successor edges

ql/src/codeql_ruby/controlflow/internal/Cfg.ql

@@ -1,3 +1,7 @@
+/**
+ * @kind graph
+ */
+
 import codeql_ruby.controlflow.ControlFlowGraph
 
 query predicate nodes(CfgNode n) { any() }
@@ -5,6 +9,6 @@ query predicate nodes(CfgNode n) { any() }
 query predicate edges(CfgNode pred, CfgNode succ, string attr, string val) {
   exists(SuccessorType t | succ = pred.getASuccessor(t) |
     attr = "semmle.label" and
-    val = t.toString()
+    if t instanceof SuccessorTypes::NormalSuccessor then val = "" else val = t.toString()
   )
 }