Unit test timeout value too short for systems with slow disks

When building NiFi on a VM with relatively old disks, a unit test consistently fails due timing out. The unit test in question is:

TestStandardFlowFileQueue.testListFlowFilesResultsLimitedCollection

Extend the timeout from 5 sec to 10 sec. The value of 10 allows consistent passing of this unit test. On systems with faster disks, this increase in timeout will be inconsequential, i.e. will not slow down the build. Yet, the extension will allow compilation on older systems.