add dependency check in cost_aware_partition (#47856)
Summary:
In the cost_aware_partition, check the circular dependency in try_combining_partitions. Also fix the calculate of communication time between partitions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47856
Reviewed By: gcatron
Differential Revision: D24926591
Pulled By: scottxu0730
fbshipit-source-id: c634608675ac14b13b2370a727e4fb05e1bb94f0
