Fix testInstancesStoppable_zoneBased

[NealSun96]

The changes merged in #858 broke testInstancesStoppable_zoneBased. The test didn't create external views at all, which will encounter exceptions with the new logic.
The logic added wasn't supposed to break the tests because the logic is to perform null checks before an if condition that utilizes maps. However, the tests were passing because in the "and" if condition, it failed at isPartitionMap.containsKey(instanceName) without accessing the second part of the "and" condition. Therefore, even though the second part could cause an null pointer failure, it was never an issue. The fix is to reorder the logic such that the conditions are performed separately with null checks right before each map access.