Remove project_imports method from usage_data
Description
As a part of the effort to remove usage_data.rb file we can now remove project_imports
method.
The metrics were added earlier, within this issue we just need to update metric definitions (to use the instrumentation classes) and removed the method with all the associated specs.
No new specs are necessary here, since our instrumentation frameworks covers usage of the classes.
Edited by Niko Belokolodov