[2.3.0] Checkmk Werk 16403 created: Fix assert self._rulespec.item_name is not None

[//]: # (werk v2) # Fix assert self._rulespec.item_name is not None key | value ---------- | --- date | 2024-02-13T10:08:20+00:00 version | 2.3.0b1 class | fix edition | cre component | wato level | 1 compatible | yes A `rulespec` may have an `item_spec` without a title. In [Werk #13387](https://checkmk.com/werk/13387) changed it so that if this title is missing the the following crash occurs. ``` assert self._rulespec.item_name is not None ``` The occured if one navigates to the parameters via `Parameters for this service` and clicks `Parameters`. It is now fixed.