Ensure that the integration test include dirs correspond to that of libminifi

Background:

We currently need to use somewhat convoluted includes when building integration tests, eg.:

#include "../../../libminifi/test/TestBase.h"

Proposal:

We should verify, that the target_include_directories specified for integration tests are similar to those of libminifi and then replace the obscure include patterns. Looking through all includes that start with ".." should probably be sufficient.