Avoid searching for Jupyter when using Raw Kernels (when Python runtime isn't necessary)

[DonJayamanne]

Today even when a user is working on non-python kernels, we attempt to look for Jupyter, even when this isn't required.

[DonJayamanne]

Testing
Again, testing has been covered in other issues.
Bascially in the past even when using raw kernels, we'd perform a search for an Interpreter that supports Jupyter.
Now that code path isn't executed anymore.