Fix checksum unit tests on dev_4_4 (see #11381)

This PR fixes some of the errors encountered during the ``test-unit`` build target. The ``rendering`` component was including the ``common-test.jar`` file and executing unit tests from it two, which was test execution doubling. Additionally, the unit tests in ``common`` relied on files not included in the output test jar - this has now been corrected.

To test:
- execute ``build.py test-unit`` and make sure that the error mentioned in https://trac.openmicroscopy.org.uk/ome/ticket/11381 doesn't happen anymore.

This PR will have to be rebased onto develop with additional changes to develop-specific checksum provider tests.