project builders cleaned up too aggressively.

releng.control/cleanupArtifacts.sh

@@ -178,7 +178,7 @@ removeOldDirectories ${PROJECT_TESTS} 1;
 
 echo " ";
 echo "INFO: Checking to remove old project builder directories."
-removeOldDirectories ${PROJECT_BUILDERS} 1;
+removeOldDirectories ${PROJECT_BUILDERS} 3;
 
 echo " ";
 echo "INFO: Checking to remove old tmp directories and files."