Back port JBSEM-4629 Disable default behaviour of auto-save for process instances

Continuous registering for auto-save can cause performance issues as when the jbpmContext closes it will save all instances in the autoSaveProcessInstances list which can be huge.

The proposed fix is to change to the code to:

if (processId!=null)

{ return ManagedJbpmContext.instance().getProcessInstance(processId); }