Stabilize TestInstanceOperation (#2715)

* Stabilize TestInstanceOperation. clusterVerifier is evaluating to true once the partitionAssignment matches the expected value; however, it is before the TopState is transfered back to the SWAP_IN node. This can be fixed by using TestHelper.verify to check that states converge within TIMEOUT.

* Moved evacuate tests with long ST resources to the end because it was taking long time to drop DBs which was causing flakyness in later tests. Ran TestInstanceOperation 5 times locally with success.