Update XFAIL conditions of matrix_elementwise_vector_cast and matrix_trunc_cast to match runner results

[Icohedron]

The two tests are XPASSing on all machines except Intel under Vulkan with Clang. See:

• [Intel][Vulkan][Clang] Basic/Matrix/matrix_elementwise_vector_cast.test fails on Intel under Vulkan with Clang #591
• [Intel][Vulkan][Clang] Basic/Matrix/matrix_trunc_cast.test fails on Intel under Vulkan with Clang #592

But I believe the existing linked issue for the XFAIL is still the most relevant one so I did not change the linked bug.
#591 and #592 can probably be closed as duplicates of #599.

[farzonl]

hmm if this is a driver bug maybe it shouldn't be in https://github.com/llvm/llvm-project and instead we should close #599.

[Icohedron]

hmm if this is a driver bug maybe it shouldn't be in https://github.com/llvm/llvm-project and instead we should close llvm/offload-test-suite#599.

We can also transfer the issue from llvm-project to the offload-test-suite repo. I believe the issue link will also redirect to the new one if we do that.

edit: I transferred the issue and I have made a commit to change the link to point to the new issue under the offload-test-suite. (which isn't necessary, as the old link redirects to the new one, but I still did it anyways).