C#: Refactor how simpleLocalFlowStep is called

`localFlowStep` is no longer an alias because it should not have the
same QLDoc as `simpleLocalFlowStep`.

Author: jbj

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -220,14 +220,6 @@ module LocalFlow {
   }
 }
 
-/**
- * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
- * (intra-procedural) step.
- */
-predicate localFlowStepImpl(Node nodeFrom, Node nodeTo) {
-  simpleLocalFlowStep(nodeFrom, nodeTo)
-}
-
 /** A collection of cached types and predicates to be evaluated in the same stage. */
 cached
 private module Cached {
@@ -258,8 +250,6 @@ private module Cached {
     TMallocNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getElement() instanceof ObjectCreation }
 
   /**
-   * INTERNAL: do not use.
-   *
    * This is the local flow predicate that's used as a building block in global
    * data flow. It may have less flow than the `localFlowStep` predicate.
    */

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPublic.qll

@@ -147,7 +147,11 @@ ExprNode exprNode(DotNet::Expr e) { result.getExpr() = e }
  */
 ParameterNode parameterNode(DotNet::Parameter p) { result.getParameter() = p }
 
-predicate localFlowStep = localFlowStepImpl/2;
+/**
+ * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
+ * (intra-procedural) step.
+ */
+predicate localFlowStep(Node nodeFrom, Node nodeTo) { simpleLocalFlowStep(nodeFrom, nodeTo) }
 
 /**
  * Holds if data flows from `source` to `sink` in zero or more local