Unshare event is missing

[MorrisJobke]

• userA shares a file to userB
• userB unshare the file
• expected: userA & userB should see an "userB unshared file" event in the activity stream
• actual: there is none

This shows: admin shared and unshared and then admin shared and test unshared (last one is missing):

cc @nickvergessen

Might be related to nextcloud/server#12062

[nickvergessen]

Also unshare for mail shares is missing, investigating