Fix and enable DALI tests
This pull request **introduces 1 alert** when merging af670381c65ac34248df3ca92a7decefe00e40f8 into 00c5429902c5bf8a1ff3efbdff16aa8935ace8d9 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-85e49b514fdccac71e3d647f3e3a3c42454826a7)

**new alerts:**

* 1 for Unused import Closing in favor of #2077 
Signed-off-by: Joaquin Anton <janton@nvidia.com>