[clang] [clang] require arg list in type specifiers using template kw (PR #94674)

[Aaron Ballman via cfe-commits]

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

LGTM -- no release note needed because this is a follow-up to work that already has a release note.

https://github.com/llvm/llvm-project/pull/94674