Mark XLA Linux jobs as unstable temporarily (#92634)
To be reverted once the issue is mitigated https://hud.pytorch.org/failure/%5B%20%20FAILED%20%20%5D%20AtenXlaTensorTest.TestFrobeniusNormInDims
Caused by https://github.com/pytorch/pytorch/pull/81763
Pull Request resolved: https://github.com/pytorch/pytorch/pull/92634
Approved by: https://github.com/ZainRizvi
