[Bug]: (CalDav|CardDav) unsharing calendar as owner leads to wrong state

[kesselb]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

Removing the share for a user who has access to the calendar through a team/group membership leads to "wrong" state in the database.

Steps to reproduce

• Users: Admin, Bob
• Teams/Circle: A-Team (Members: Admin, Bob)

1. Login as admin
2. Create a calendar "A-Team"
3. Share calendar "A-Team" to team/circle "A-Team"
4. Remove "A-Team" calendar share for "A-Team"

(see below for database excerpts)

Expected behavior

Removing a calendar share as calendar owner should remove the related record in oc_dav_shares.
There should be no new row with access = 5 (unshare) if the action was done as calendar owner.

Additional info

oc_dav_shares after step 3:

oc_dav_shares after step 4: