[MIE-1434] add verb to deleteSpecificActivity endpoint response

I add the deleted activity verb to the response to be able to know from front-end, the verb of the activity we need to remove. 
But this data is obviously not necessary for this respond because we are not using it. I think adding unused data to payload is silly; we should aim to reduce our payload size wherever possible. If you see a future use for this data or if you really want to add this, then please at least document what you are doing with code comments.