sn_change_cab_notify_all_attendees is action name being used in Notify All Attendees Ui action and which is getting called from Send meeting request to attendees via that action name. Events are getting triggered by Notify All Attendees UI action. See screenshot below.

Above Ui action is calling CABMeeting() script include and that script include calling another script include. 

I would recommend not to go that deep into the script as you are not very into scripting so will be lost. 

If you know how to script a scheduled job, just wrap two server side functions I explained in the first UI action into the Script include and call from the job with minor tweaks. It will do the job. 

Please mark this accepted & helpful, if it helps.

Thanks & Regards,

Sharjeel