UP-3998 ignore JpaClusterLockDaoTest.testConcurrentCreateLocking().

because it is non-deterministically false-failing.

See also:
* [UP-3998](https://issues.jasig.org/browse/UP-3998)
* [uportal-user@ discussion](http://thread.gmane.org/gmane.comp.java.jasig.uportal/16875)