erp5testnode and taskdistributor are not using Distributor endpoint for createTestResult call, but Tool.

This fix changes it to use Distributor call instead of Tool call and also removes not needed TaskDistributionTool class.

Code keeps compatibility, as server might not implement Distributor.createTestResult call correctly - the client will detect such situation and will call Tool.createTestResult as fallback.

Tasks:

• drop backward compatibility in erp5/util/taskdistribution/__init__.py