[clang] [Clang] Fix various bugs in alias CTAD transform (PR #132061)

[Younan Zhang via cfe-commits]

================
@@ -1467,10 +1477,16 @@ namespace {
       }
     }
 
-    static TemplateArgument
+    bool HeuristicallyComputeSizeOfPackExpr() const {
+      return !TemplateArgs.isRewrite();
+    }
+
+    TemplateArgument
----------------
zyn0217 wrote:

It is intended because we need to access `SemaRef.ArgumentPackSubstitutionIndex`

https://github.com/llvm/llvm-project/pull/132061