Revert "send invitations for shared calendars"
Revert "send invitations for shared calendars"

This reverts commit a9c313ce451c701a2e065e34022659cf17523963.

andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server