[BUG]: Spark .NET gives preference to DLLs existing on the worker nodes on top of different version DLLs packaged through the customer application

**Describe the bug**
Spark .NET gives preference to DLLs existing on the worker nodes on top of different version DLLs packaged through the customer application. This causes user applications depending on their DLL version fail with the following error:

```
System.TypeLoadException: Could not load type 'ABC' from assembly 'XYZ, Version=1.0.0.0, Culture=neutral, PublicKeyToken=qwertyui'
```

**Expected behavior**
Spark .NET should give preference to and load user specified DLLs while running the tasks on the worker.

**Additional context**
Related to issue - https://github.com/dotnet/spark/issues/732