Wait for safe state for only nodes which used in the test

closes https://github.com/hazelcast/hazelcast/issues/4235
My fix was going to be:
```java
Set<HazelcastInstance> nodeSet = factory.getAllHazelcastInstances()
```
and make the methods `isAllInSafeState`,`waitAllForSafeState` non static. That way we automatically get instances that are only used in this test and don't need to specify them.