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0fc25715 - fix a bug in 2nd order schedulers when using in ensemble of experts config (#5511)

fix a bug in 2nd order schedulers when using in ensemble of experts config (#5511) * fix * fix copies * remove heun from tests * add back heun and fix the tests to include 2nd order * fix the other test too * Apply suggestions from code review * Apply suggestions from code review * Apply suggestions from code review * make style * add more comments --------- Co-authored-by: yiyixuxu <yixu310@gmail,com> Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>