[mlir] [MLIR][Vector] Remove unused and unimplemented Vector_WarpExecuteOnLa… (PR #112338)

[Andrzej Warzyński]

https://github.com/banach-space approved this pull request.

LGTM, we can always restore it when needed. @kuhar, any reason not to delete this?

https://github.com/llvm/llvm-project/pull/112338