test: fix Nextcloud 33 test failures caused by trashbin UID conflicts

Nextcloud 33 introduced (or changed) soft-delete behaviour: when a calendar
is deleted via CalDAV, both the calendar and its objects are soft-deleted to
a trashbin.  When tests delete and re-create a calendar with the same slug,
Nextcloud reuses the same calendarid, and the soft-deleted objects (with their
UIDs) remain in oc_calendarobjects.  Trying to add a new event with the same
UID then fails with "UNIQUE constraint failed: calendarid, calendartype, uid".

Fix: set calendarRetentionObligation=0 in setup_nextcloud.sh.  When this
config value is the string '0', CalDavBackend::deleteCalendar and
deleteCalendarObject skip the trashbin entirely and hard-delete immediately
(see apps/dav/lib/CalDAV/CalDavBackend.php lines 940-941, 1572).  Also run
dav:retention:clean-up at startup to purge any leftover soft-deleted entries
from prior runs.

Also update the nextcloud compatibility hints to reflect the changed behaviour
of scheduling.mailbox.inbox-delivery in Nextcloud 33: the server now delivers
the iTIP notification to the inbox AND auto-schedules into the attendee's
calendar (quirk), whereas previously it only delivered to the inbox (full).

Prompt: `pytest -k nextcloud --last-failed` gives lots of failures.  It seems
to be something wrong with the nextcloud container.  Looks a bit like the
problems are due to the setup (user provisioning) is not being compatible with
the latest version of the image.  Please investigate.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tobixen

caldav/compatibility_hints.py

@@ -945,7 +945,10 @@ def dotted_feature_set_list(self, compact=False):
     'principal-search': {'support': 'ungraceful'},
     #'old_flags': ['unique_calendar_ids'],
     ## I'm surprised, I'm quite sure this was passing earlier.  Caldav commit a98d50490b872e9b9d8e93e2e401c936ad193003, caldav server checker commit 3cae24cf99da1702b851b5a74a9b88c8e5317dad
-    'search.combined-is-logical-and': False
+    'search.combined-is-logical-and': False,
+    ## Observed with Nextcloud 33: server delivers iTIP notification to the inbox AND
+    ## auto-schedules into the attendee's calendar (same quirk as Baikal/Cyrus).
+    "scheduling.mailbox.inbox-delivery": {"support": "quirk", "behaviour": "server delivers iTIP notification to inbox AND auto-schedules into calendar"},
 }
 
 ## TODO: Latest - mismatch between config and test script in delete-calendar.free-namespace ... and create-calendar.set-displayname?

tests/docker-test-servers/nextcloud/setup_nextcloud.sh

@@ -61,6 +61,17 @@ fi
 docker exec $CONTAINER_NAME php occ app:disable bruteforcesettings || true
 docker exec $CONTAINER_NAME php occ config:system:set auth.bruteforce.protection.enabled --value=false --type=boolean || true
 
+echo "Disabling CalDAV trashbin (calendar retention)..."
+# Setting calendarRetentionObligation to '0' (the string) disables the trashbin in
+# CalDavBackend::deleteCalendar and deleteCalendarObject, making deletes permanent.
+# Without this, deleted calendars/objects are soft-deleted and accumulate in the DB,
+# causing UNIQUE constraint violations when tests recreate a calendar with the same slug
+# (Nextcloud 33+ reuses the calendarid, keeping old soft-deleted objects, so adding
+# an event with the same UID fails).
+docker exec $CONTAINER_NAME php occ config:app:set dav calendarRetentionObligation --value=0 || true
+# Purge any leftover soft-deleted calendars/objects from previous runs
+docker exec $CONTAINER_NAME php occ dav:retention:clean-up || true
+
 echo "Configuring CalDAV rate limits..."
 docker exec $CONTAINER_NAME php occ config:app:set dav rateLimitCalendarCreation --value=99999 || true
 docker exec $CONTAINER_NAME php occ config:app:set dav maximumCalendarsSubscriptions --value=-1 || true