[clang] [clang][NFC] Spell out DynTypedNode instead of auto (PR #114427)

[Chris Cotter via cfe-commits]

ccotter wrote:

While working on #114244, I noticed the use of `auto` in `memberHasSameNameAsBoundNode`. The only other place I could find using `auto` with `Nodes.getNode` was in the second file I changed.

https://github.com/llvm/llvm-project/pull/114427