[clang] [Clang] Fix AST dump for {CXXDefaultArgExpr, CXXDefaultInitExpr} (PR #88269)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

LGTM but you should check JSONNodeDumper.cpp as well to see if it needs similar changes.

https://github.com/llvm/llvm-project/pull/88269