Improvements to MongoDB integration tests

Separates the integration tests to allow different configurations for different tests, for example to make sure the connector in the `oldDocuments` tests actually uses that collections, and sets the correct limit.
Should probably speed up the tests marginally, as they no longer insert 2000 documents just to test that the collection is capped.

Removes the many calls to the status updater thread in `testRollover`, hopefully making it more stable.

Fixes two ignored tests for handling of documents large than MongoDB max size. They were ignored a long time ago, probably because they cause OOM errors due to serializing 16 MB JSON in memory. There should also be a speed up here, since the serialization of such large documents take up to several seconds.

Adds ignores for temporary pipeline directories created by the test-suite and when starting the Hydra Core jar from the root.