Update __init__.py (facebookresearch#4086)

Summary:
X-link: meta-pytorch/torchrec#2628

Fix erroneous logging `Failed to load GPU Faiss: No module named 'swigfaiss_gpu'. Will not load constructor refs for GPU indexes.` when I was running on a GPU-based index just fine.

`GpuIndex...` is loaded via loader.py.

Pull Request resolved: facebookresearch#4086

Test Plan:
before
```
(faiss_gpu_cuvs_nightly) [[email protected] ~]$ python3 script.py
Failed to load GPU Faiss: No module named 'swigfaiss_gpu'. Will not load constructor refs for GPU indexes.
```

after
```
(faiss_gpu_cuvs_nightly) [[email protected] ~]$ python3
Python 3.12.8 | packaged by conda-forge | (main, Dec  5 2024, 14:24:40) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import faiss
>>>
```

Reviewed By: mnorris11

Differential Revision: D67118292

Pulled By: asadoughi

fbshipit-source-id: aa05aa20fe61e4ad75d4234f52e3b0d6a673a0b9

Author: Amir Sadoughi

faiss/python/__init__.py

@@ -9,6 +9,7 @@
 # causes a ton of useless warnings.
 
 import numpy as np
+import logging
 import sys
 import inspect
 
@@ -30,6 +31,8 @@
                             FAISS_VERSION_MINOR,
                             FAISS_VERSION_PATCH)
 
+logger = logging.getLogger(__name__)
+
 class_wrappers.handle_Clustering(Clustering)
 class_wrappers.handle_Clustering1D(Clustering1D)
 class_wrappers.handle_MatrixStats(MatrixStats)
@@ -161,14 +164,13 @@ def replacement_function(*args):
 
 
 try:
-    from swigfaiss_gpu import GpuIndexIVFFlat, GpuIndexBinaryFlat, GpuIndexFlat, GpuIndexIVFPQ, GpuIndexIVFScalarQuantizer
     add_ref_in_constructor(GpuIndexIVFFlat, 1)
     add_ref_in_constructor(GpuIndexBinaryFlat, 1)
     add_ref_in_constructor(GpuIndexFlat, 1)
     add_ref_in_constructor(GpuIndexIVFPQ, 1)
     add_ref_in_constructor(GpuIndexIVFScalarQuantizer, 1)
-except ImportError as e:
-    print("Failed to load GPU Faiss: %s. Will not load constructor refs for GPU indexes." % e.args[0])
+except NameError as e:
+    logger.info("Failed to load GPU Faiss: %s. Will not load constructor refs for GPU indexes." % e.args[0])
 
 add_ref_in_constructor(IndexIVFFlat, 0)
 add_ref_in_constructor(IndexIVFFlatDedup, 0)