dev/core#2057 Reduce queries when calling activity.create

dev/core#2057 Reduce queries when calling activity.create

This reduces queries in 2 ways
1) if the action is 'create' then existing activity contacts cannot exist, so do not try to delete them
2) if the action is 'edit' then look for & delete for all 3 record types at once.

There are still questions about how we can improve this further but it should remove up to 3 queries per
Activity.create call