[llvm] [llvm] Avoid 'raw_string_ostream::str()' (NFC) (PR #96995)

[Youngsuk Kim via llvm-commits]

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@@ -148,7 +148,7 @@ std::string CompleteNodeLabelString(
   std::string Str;
   raw_string_ostream OS(Str);
   HandleBasicBlock(OS, *Node);
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JOE1994 wrote:

Applied your feedback to follow-up commit. Thank you!

https://github.com/llvm/llvm-project/pull/96995