c11_atomics `{svm_,}atomic_fence` test issues

[kpet]

Several implementers have reported issues over the years with the atomic_fence and svm_atomic_fence tests, the latest being #2496.

Analysis from a few years ago (e.g. https://www.khronos.org/members/login/bugzilla/show_bug.cgi?id=15814) suggests that the tests are incorrect and make assumptions that are not guaranteed to hold. This was discussed in the 2025/10/14 teleconference and we agreed to disable the tests and create this issue for tracking.

[Sai-Kumar-Atluri]

Hi @kpet , both #2496 and https://www.khronos.org/members/login/bugzilla/show_bug.cgi?id=15814 looks like similar issue and I have provided fix for this issue here(#2485).

I would like to know do we have any other issues open on atomic_fence and svm_atomic_fence? It would be nice if we can maintain list of related issues here.