Revert "Fix import of AxModelManager"

This reverts commit d6221cc.

Author: RemiLehe

optimas/generators/__init__.py

@@ -4,8 +4,8 @@
     from .ax.service.multi_fidelity import AxMultiFidelityGenerator
     from .ax.service.ax_client import AxClientGenerator
     from .ax.developer.multitask import AxMultitaskGenerator
-except (ImportError, ModuleNotFoundError) as e:
-    if e.__str__().startswith("No module named 'ax"):
+except ImportError as e:
+    if e.__str__() == "No module named 'ax'":
         # Replace generators by dummy generators that will
         # raise an error only if the user tries to instantiate them
         # and tell them to install ax-platform

optimas/utils/ax/ax_model_manager.py

@@ -29,12 +29,8 @@
 
     ax_installed = True
 except ImportError:
-    from .import_error_dummy_class import AxImportErrorDummyClass
-    AxClient = AxImportErrorDummyClass
-    TorchModelBridge = AxImportErrorDummyClass
     ax_installed = False
 
-
 from optimas.core import VaryingParameter, Objective
 from optimas.utils.other import convert_to_dataframe