Putting back the NCCL forced upgrade. (#2999)
* Putting back the NCCL forced upgrade.
* .
* ...
* Ignoring conda.
* Dropping conda from the buidl system + torch 2.6
* Cache min.
* Rolling back torch version.
* Reverting the EETQ modification.
* Fix flash attention ?
* Actually stay on flash v1.
* Patching flash v1.
* Torch 2.6, fork of rotary, eetq updated.
* Put back nccl latest (override torch).
* Slightly more reproducible build and not as scary.
