Kill alpha build folders from previous runs

This was main culprit behind failures, since you end up with
a long chain of .alpha.alpha.alpha packages that then fail

Change-Id: Ife1e65ded0897e9b19d64f2f97739e32cb3c86cc
Request 8G of RAM for jsub

Change-Id: Idf3b290c8858b76c05d8afe97cc88d1fd7800dd2