[clang] [NFC] [clang] Use std::string instead of StringRef to reduce stack usage (PR #114285)

[Matt Arsenault via cfe-commits]

https://github.com/arsenm commented:

If you really want to work around MSVC's bug, you could change tablegen to emit the string literals as constant globals / StringLiteral 

https://github.com/llvm/llvm-project/pull/114285