Only run 4 instances max in churn.
Only run 4 instances max in churn.

Change-Id: I0e559e7b8b04a0b5227de2eeea3ff451eef4dc3c

tbeckham/eutester,nephomaniac/nephoria,sjones4/eutester,shaon/eutester,nagyistoce/eutester,shaon/eutester,sjones4/eutester,nagyistoce/eutester,sjones4/eutester,nephomaniac/eutester,shaon/eutester,nagyistoce/eutester,nephomaniac/eutester,tbeckham/eutester,nephomaniac/eutester,shaon/eutester,tbeckham/eutester,nephomaniac/nephoria,nagyistoce/eutester,sjones4/eutester,tbeckham/eutester