Only trigger the events with tags that where actually assigned

[nickvergessen]

1. Set up automated tagging with a rule like the following:

2. Create a folder and tag it
3. Upload a file inside the folder
4. Rename the file
5. Open activity in the sidebar
6. See multiple entries with Added system tag "Tag"

Fix nextcloud/files_automatedtagging#75

[blizzz]

makes sense