Move CI to cuda-11.6 (#79921)
Delete 11.6 from periodic builds and instead move them to pull/trunk
Update debug build from 11.3 to 11.6
CUDA-11.3 have number of know bugs in complex cublas/sparse support as well as performance issue with NVRTC
Pull Request resolved: https://github.com/pytorch/pytorch/pull/79921
Approved by: https://github.com/ngimel, https://github.com/atalman, https://github.com/seemethere
