Flaky HBase test: containsKeyColumnReturnsFalseOnNonexistentInput

```java
[ERROR] Failures:
[ERROR] HBaseStoreTest>KeyColumnValueStoreTest.containsKeyColumnReturnsFalseOnNonexistentInput:924 expected: but was:
```

Job was:
```
MODULE='hbase-parent/janusgraph-hbase-10' INSTALL_ARGS='-Dhbase.profile -Phbase2' ARGS='-Dtest=**/diskstorage/hbase/* -Dhbase.profile -Phbase2'
```

[The build](https://travis-ci.org/JanusGraph/janusgraph/builds/500329208) were the job failed but worked after being restarted.

Start with HBaseStoreTest.containsKeyColumnReturnsFalseOnNonexistentInput at test line 924 and reproduce it using the reported hbase-parent/janusgraph-hbase-10 module command. Compare the HBase profile runs that fail and pass, then identify a fix or test adjustment that makes the nonexistent-input assertion reliably return false.

Written by the indexing model from the issue text.