Remove lenient stubbing from ConditionLinkSetMapper

* Refactor `ConditionLinkSetMapper` to remove lenient stubbing.
* Inline single use constants.
* Move shared stubbing to reusable methods.
* Regroup / extract tests from parameterized tests which relied on lenient mocking.
* Move condition tests code to `CodeableConceptMapperMockUtil`.

Author: MartinWheelerMT