Enable iterative benchmark tests or put in a profile

These tests are commented out but should be controlled by a maven profile or some similar mechanism.

https://github.com/JanusGraph/janusgraph/blob/01fc5b66725443a67e549be6a05c54e71eec655a/janusgraph-test/src/main/java/org/janusgraph/graphdb/JanusGraphIterativeBenchmark.java#L57

https://github.com/JanusGraph/janusgraph/blob/01fc5b66725443a67e549be6a05c54e71eec655a/janusgraph-test/src/main/java/org/janusgraph/graphdb/JanusGraphIterativeBenchmark.java#L84

Start with the commented benchmark sections at lines 57 and 84 of janusgraph-test/src/main/java/org/janusgraph/graphdb/JanusGraphIterativeBenchmark.java, then inspect the repository's Maven configuration. Determine how a profile or similar mechanism should control these tests, and verify that the benchmarks can be enabled through that mechanism.

Written by the indexing model from the issue text.