fixes #6856 - API v2 - more efficient import puppetclasses for single environment

This test passes with and without the patch. Environments are imported properly when the parameter is passed. What is not imported properly is puppetclasses. 

A suggestion on how to test this is to make ```env1``` return puppetclass ```a``` and make ```env2``` return puppetclass ```b```, and then check that this query only adds puppetclass ```a``` to the list of our puppetclasses, and not ```b```. Removing the environments for this test is not needed, only the puppetclasses.

In order to do this you'll need to change some expectations of ProxyAPI::Puppet, since ```setup_import_classes``` makes it import the same puppetclasses for all environments.