[clang-tools-extra] [clang-tools-extra] Apply modernize-use-string-view to the code (PR #179514)

[via cfe-commits]

================
@@ -634,7 +634,7 @@ std::string IdentifierNamingCheck::HungarianNotation::getDataTypePrefix(
   return PrefixStr;
 }
 
-std::string IdentifierNamingCheck::HungarianNotation::getClassPrefix(
+llvm::StringRef IdentifierNamingCheck::HungarianNotation::getClassPrefix(
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zeyi2 wrote:

```suggestion
StringRef IdentifierNamingCheck::HungarianNotation::getClassPrefix(
```

WDYT? Will removing `llvm::` trigger a `modernize-use-string-view` warning?

https://github.com/llvm/llvm-project/pull/179514