Notifications of new big folder do not disapear when the folder is removed on the server

[ogoffart]

Reported by @Dianafg76 in #3148 (comment)

in 2.0 beta1.

Original comment bellow:

I tried this, and I have a quenstion :

1. I have 2 users (user1 , user2 )
2. User 1 , I have a folder called MP4 files over 500 MB ( for example , 612 MB ​​)
3. I go to the server and share the folder (MP4 files) for user 2
4. Go to the desktop client user- 2 appears: There are new folders that.....", This is OK
   
5. I go to the server again, and I have removed the option to share with usuario2
6. I go to the client desktop user 2 and has not disappeared folder (MP4 files) .
   

[ogoffart]

This is sort of done, meaning that it will disapear next time the selective sync tree view is refreshed. (but that does not happen automatically)