[llvm] [DebugInfo] Remove class and function names from Doxygen comments in LexicalScopes.h (NFC) (PR #159310)

[David Blaikie via llvm-commits]

dwblaikie wrote:

(If you're creating a PR just for presubmit checks, not intending it to be reviewed/approved-before-commit, please be sure to include the `skip-precommit-approval` tag on it so it doesn't look like a case of "I sent this for review and then committed it without the required review")

Thanks for the cleanup!

https://github.com/llvm/llvm-project/pull/159310