[nnc] Test case for computeAt with reduction (#54755)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54755
As title. A step on the way to using computeAt to optimize
convolution.
ghstack-source-id: 125054730
Test Plan: new test
Reviewed By: ZolotukhinM
Differential Revision: D27353663
fbshipit-source-id: 930e09d96d1f74169bf148cd30fc195c6759a3e9
