[clang-tools-extra] [clang] remove ClassScopeFunctionSpecializationDecl (PR #66636)

[Piotr Zegar via cfe-commits]

================
@@ -67,7 +67,7 @@ AST_MATCHER_P(CallExpr, hasLastArgument,
 // function had parameters defined (this is useful to check if there is only one
 // variadic argument).
 AST_MATCHER(CXXMemberCallExpr, hasSameNumArgsAsDeclNumParams) {
-  if (Node.getMethodDecl()->isFunctionTemplateSpecialization())
+  if (Node.getMethodDecl()->getPrimaryTemplate())
----------------
PiotrZSL wrote:

```
  if (const FunctionTemplateDecl* PrimaryTemplate = Node.getMethodDecl()->getPrimaryTemplate())
    return Node.getNumArgs() == PrimaryTemplate->getTemplatedDecl()->getNumParams();
```

https://github.com/llvm/llvm-project/pull/66636