Change test cases to use ad-hoc repositories

[soenkeliebau]

As part of 5f5a1f1 the ability to create ad-hoc repositories which are served by the test driver has been added to the test suite.

This has not yet been implemented in all test cases but should be refactored as time permits.

[siegfriedweber]

This issue will be obsolete when the ad-hoc repository is used in all test cases.

[lfrancke]

@soenkeliebau @siegfriedweber Is this still relevant?