LPS-47269 remove EVENT_UPDATE sync event when checking for locks

Hey @dejuknow 

This is the pull that I told you about when I was in LA about removing the sync EVENT_UPDATE in order to know when a document is no longer checked out (because it expired)

We'd like to remove this line and then you would need to take care of storing the expiration date and handle that on your end.

Can we go ahead and merge this?

cc/ @mikemanyoung @shinnlok @adolfopa 

Thanks!