[2.3.0] Checkmk Werk 16763 created: do not display empty groups in rule editor

[//]: # (werk v2) # do not display empty groups in rule editor key | value ---------- | --- date | 2024-05-08T12:22:20+00:00 version | 2.3.0p2 class | fix edition | cre component | checks level | 1 compatible | yes This only affects plugin developers. In the rule editing interface, empty `DictGroup`s (`DictGroup`s with all `DictElement`s only rendered, so not editable) were displayed. This werk fixes that behaviour, so if every `DictElement` inside a `DictGroup` is rendered only, the corresponding `DictGroup` will not be shown in the interface.