New ProblematicTest.class in MapEvictAllTest

The test com.hazelcast.map.MapEvictAllTest.testEvictAll_onBackup() fails randomly in the actual master branch. I added the category ProblematicTest.class and a short example of the occuring assertion error.

In addition I cleaned up the test class (get rid of all warnings due to missing generic definitions and unwanted final keyword on variables).
Can you verify the failure by using assertTrueEventually?
```
 assertTrueEventually(new AssertTask() {
            @Override
            public void run() throws Exception {
                assertEquals(0, map1.getLocalMapStats().getHeapCost());
            }
        });

```