Remove redundant profiling imports

Created by: thesps

Remove two imports from profiling module which are no longer needed. With qkeras in the main import list, the profiling module could not be imported into an environment without qkeras. I think that's why the profiling section of the docs is blank. But it didn't need to be there anyway, since this try/except section handles it.

I also removed the import importlib since that's an artefact from when we handled the imports differently. I checked that the profiling does still work and produce plots when TF and qkeras are there, too.