Ruby: Disable summaries that clash with Array

Some String methods are named identically to Array methods, and this
leads to overlapping flow summaries. These adversely affect the original
Array flow summaries.

ruby/ql/lib/codeql/ruby/frameworks/core/String.qll

@@ -175,7 +175,12 @@ module String {
    * A flow summary for `String#concat` and `String#prepend`.
    */
   private class ConcatSummary extends SimpleSummarizedCallable {
-    ConcatSummary() { this = ["concat", "prepend"] }
+    ConcatSummary() {
+      // `concat` and `prepend` omitted because they clash with the summaries for
+      // `Array#concat` and `Array#prepend`.
+      // this = ["concat", "prepend"]
+      none()
+    }
 
     override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
       input = ["Receiver", "Argument[_]"] and
@@ -304,7 +309,11 @@ module String {
    * A flow summary for `String#insert`.
    */
   private class InsertSummary extends SimpleSummarizedCallable {
-    InsertSummary() { this = "insert" }
+    InsertSummary() {
+      this = "insert" and
+      // Disabled because it clashes with the summary for Array#insert.
+      none()
+    }
 
     override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
       (