Removed distributor tests that were tied to the old importer

The export distributor tests are an utter mess. They had multiple areas that relied on the old yum importer. On top of that, the tests themselves were difficult to read, contained many (like, seriously, a lot) of unused variables and no description of what the test was trying to achieve. Rather than trying to unravel these, I'm putting on the backlog a story to revisit and write proper tests.