[clang][NFC] Remove useless code in ASTWriter

A follow-up to #71709, addressing the static analysis finding reported in https://github.com/llvm/llvm-project/pull/71709/files#r1576846306

Author: Endilll

clang/lib/Serialization/ASTWriter.cpp

@@ -3618,7 +3618,6 @@ class ASTIdentifierTableTrait {
   /// doesn't check whether the name has macros defined; use PublicMacroIterator
   /// to check that.
   bool isInterestingIdentifier(const IdentifierInfo *II, uint64_t MacroOffset) {
-    II->getObjCOrBuiltinID();
     bool IsInteresting =
         II->getNotableIdentifierID() !=
             tok::NotableIdentifierKind::not_notable ||