Update slow CI jobs to rocm5.6 (#105516)
Follow-up to https://github.com/pytorch/pytorch/pull/103092, which missed updating the slow CI jobs to ROCm5.6, as they were recently moved to slow.yml by https://github.com/pytorch/pytorch/commit/def50d253401540cfdc6c0fffa444d0ee643cc11
Pull Request resolved: https://github.com/pytorch/pytorch/pull/105516
Approved by: https://github.com/huydhn, https://github.com/malfet
