public static synchronized void destroyRegions() {
    Cache cache = GemFireCacheImpl.getInstance();
    if (cache != null) {
      Region region = cache.getRegion(regionName);
      if (region != null) {
        region.destroyRegion();
      }
    }
  }
Tear down a PartitionedRegionTestCase by cleaning up the existing cache (mainly because we want
to destroy any existing PartitionedRegions)
geode-core/src/distributedTest/java/org/apache/geode/cache/query/internal/index/ConcurrentIndexUpdateWithoutWLDUnitTest.java