[TableGen] Use StringRef::contains (NFC) (llvm#141413)

Author: kazutakahirata

clang/utils/TableGen/SveEmitter.cpp

@@ -252,9 +252,7 @@ class Intrinsic {
   /// a short form without the type-specifiers, e.g. 'svld1(..)' instead of
   /// 'svld1_u32(..)'.
   static bool isOverloadedIntrinsic(StringRef Name) {
-    auto BrOpen = Name.find('[');
-    auto BrClose = Name.find(']');
-    return BrOpen != std::string::npos && BrClose != std::string::npos;
+    return Name.contains('[') && Name.contains(']');
   }
 
   /// Return true if the intrinsic takes a splat operand.