[clang-tools-extra] [clang-tidy][NFC] Make a few `std::string`s into `StringRef`s (PR #160961)

[Carlos Galvez via cfe-commits]

================
@@ -33,8 +33,8 @@ class ExceptionEscapeCheck : public ClangTidyCheck {
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
 
 private:
-  std::string RawFunctionsThatShouldNotThrow;
-  std::string RawIgnoredExceptions;
+  StringRef RawFunctionsThatShouldNotThrow;
----------------
carlosgalvezp wrote:

I have a bit of mixed feelings about this since it can lead to lifetime issues. But I see the change you mentioned in the commit message and has been applied in many other checks so I guess it's fine!

https://github.com/llvm/llvm-project/pull/160961