[clang] [clang][sema] consolidate diags for incompatible_vector_* (PR #83609)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

@pow2clk force doesn't seem necessary b\c squash merge is the default behavior for this project. I did it because i tend to rebase my branches when I put out revisions.  I'll stop doing that.

https://github.com/llvm/llvm-project/pull/83609