[FSDP] Use INFO instead of DETAIL for warning logs (#102639)
Since these are just logs and don't introduce any big perf slowdowns,
I think we should just enable them in info mode.
Differential Revision: [D46328510](https://our.internmc.facebook.com/intern/diff/D46328510/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/102639
Approved by: https://github.com/awgu
