[clang] [Clang][Diagnostics] Update select uses in DiagnosticXKinds.td to use enum_select (PR #130868)

[Erich Keane via cfe-commits]

erichkeane wrote:

Latest patch looks right!  Just change the Github subject and Commit message to better reflect what this patch is doing, and I can approve.  IF that happens, either merge yourself (if you have permissions), or ping me  after CI is happy, and I'll merge this for you.

https://github.com/llvm/llvm-project/pull/130868