Fix to enable loading fp16 repo variant ControlNets (#8643)

* Fix ControlNet repo variant detection for fp16 weights

* Remove ControlNet diffusers fp16 regression test

* Update invokeai/backend/model_manager/configs/controlnet.py

Co-authored-by: Lincoln Stein <lincoln.stein@gmail.com>

* style: ruff format controlnet.py

---------

Co-authored-by: Lincoln Stein <lincoln.stein@gmail.com>

Author: DustyShoe

invokeai/backend/model_manager/configs/controlnet.py

@@ -88,7 +88,9 @@ def from_model_on_disk(cls, mod: ModelOnDisk, override_fields: dict[str, Any]) -
 
         cls._validate_base(mod)
 
-        return cls(**override_fields)
+        repo_variant = {"repo_variant": override_fields.get("repo_variant", cls._get_repo_variant_or_raise(mod))}
+        args = override_fields | repo_variant
+        return cls(**args)
 
     @classmethod
     def _validate_base(cls, mod: ModelOnDisk) -> None: