TestGenerator: Fix interface names in generated test harness

Generated interfaceview did not include interface names. Function used so far for cloning interface CreationInfo included:

1. Function that actually initializes interface from other one
2. Unnecessary (for this case) logic for assigning function info that was not even invoked due to nullptr passed and null check in if block.
3. Clearing interface name if the interface was auto generated (source of the problem).

Point 2 is unnecessary and 3 is harmful in this case so the whole function was replaced by the function from point 1.