Increase flux timeout to 30min

Nextcloud and Onlyoffice can take a loooong time to deploy,
because OO depends on proper LE certs, and the large image downloads can take
a while as well (see #422).

Closes: #421

flux/nextcloud.yaml

@@ -18,4 +18,4 @@ spec:
     - secretKeyRef:
         name: nextcloud-settings
         key: values.yaml
-  timeout: 900
+  timeout: 1800