retry - enable NVFuser by default

Enable NVFuser in OSS.

Retry of #77213, because it was breaking torchvision tests.

Fix in #77471 has been verified by jjsjann123

Pull Request resolved: https://github.com/pytorch/pytorch/pull/77579

Approved by: https://github.com/eellison, https://github.com/malfet, https://github.com/atalman, https://github.com/seemethere

torch/csrc/jit/codegen/cuda/interface.cpp

@@ -111,9 +111,12 @@ class NVFuserEnabler {
     if (getCachedFuserEnabledEnvVar().has_value()) {
       return *getCachedFuserEnabledEnvVar();
     }
-    // 3. default value (if you switch this to true, make sure
-    //    to check nvfuserCanBeEnabled())
+    // 3. default value
+#ifdef FBCODE_CAFFE2
     return false;
+#else
+    return nvfuserCanBeEnabled();
+#endif
   }
 
  public: