AbstractJUnit4BaseTest.doRandomChangesToWOT(): Use diamond operator

We can use it now since we compile against Java 7.
AbstractJUnit4BaseTest.doRandomChangesToWOT(): Re-phrase comment to be
shorter

- So I don't have to wrap the line.
- It also explains what is happening here better: We check whether WOT
deals properly with using restoreOwnIdentity() to restore an OwnIdentity
which was added as a non-own Identity previously. The non-own one should
be deleted, to prevent a duplicate.
AbstractJUnit4BaseTest: Line wrap