Compute matmul dim roles with no-devices leaf domain

[jacobhinkle]

This fixes a bug introduced by #2272 in test_multidevice where we reject a matmul segment shaped like [iDIDxMo, iMi, bN, iK] for having too many M dimensions. Locally this still has a single M dimension so it is valid. This PR ignores device dims for the purposes of computing tensor roles and problem shape.

Further issues we should look into:

1. As mentioned in Generalize CombineMulSum as MatmulPatterns #2272 we should proceed to handle multiple M, N, K, and Batch dimensions, although in this case the restriction was useful for surfacing this bug.
2. Even if the matmul scheduler is completely broken or disabled, the reduction scheduler should have been able to schedule this fusion. However, it identified the reduction tensor as isResharding and removed it from the reduction_tvs list, causing a failure in scheduleReduction. We should clean up that check to be able to schedule this type of fusion as a reduction.
3. Inside the matmul scheduler we call canonicalizeMmaTvOrdering which I believe still uses rfactor domain to determine domain ordering. Instead this should be updated to use dim roles that are already computed from the MatmulPattern.
4. The rfactor domain is often used for scheduling utilities to inspect the logical size of tensors. However, because multidevice scheduling modifies the leaf domain before segmentation, we should probably audit our schedulers to ensure they use the leaf domain and ignore device dims where necessary.
5. I should also not forget to rerun !build before merging PRs 😅

[jacobhinkle]

!build --diff

[cowanmeg]

Thank you!