* Why?
There were a couple of issues with the recently merged custom model
injection for AutoDeploy + the reference implementation of nemotron
H:
- `d_mlp` was left in despite being mathematically always null (could
lead to runtime issues during sharding).
- the custom model mapping was inherited by children factories.
* What?
This commit fixes these issues, and refactors the key of the custom
implementation to be based on the name of the configuration class as
well.
Signed-off-by: William Zhang <133824995+2ez4bz@users.noreply.github.com>