[PDI-11389] Use KETTLE_MAX_JOB_TRACKER_SIZE

KETTLE_MAX_JOB_TRACKER_SIZE was not taken into consideration leading to memory leak in JobTracker
Remove items from the list instead of creating a sublist.

http://jira.pentaho.com/browse/PDI-11389
[PDI-11389][TEST] Use KETTLE_MAX_JOB_TRACKER_SIZE

Unit test for 8a20dde134f1f61ba2dc825466a9ff206b1dfcb0
Merge pull request #528 from hudak/PDI-11389

 [PDI-11389] KETTLE_MAX_JOB_TRACKER_SIZE not taken into consideration