[2.4.0] Checkmk Werk 17201 created: Decommission agent_based_api.v1 (a.k.a. Check API)

[//]: # (werk v2) # Decommission agent_based_api.v1 (a.k.a. Check API) key | value ---------- | --- date | 2024-10-17T05:17:58+00:00 version | 2.4.0b1 class | feature edition | cre component | checks level | 1 compatible | no This werk only affects users and maintainers of custom check plugins developed against the first version of the `agent_based` API (a.k.a. Check API) that was introduced in Checkmk 2.0.0 and deprecated in Checkmk 2.3.0. This first version was deprecated in [Werk #16259](https://checkmk.com/werk/16259). As of Checkmk 2.4 the plugins residing in `local/lib/check_mk/plugins/agent_based` will no longer be loaded in Checkmk version 2.4. We understand this is an inconvenience to users, but are confident that this step increases the overall user experience. While not directly visible, removing this API version significantly increases maintainablity of the backend, freeing developer ressources. As of Checkmk version 2.4 plugins in that folder will generate a CRITICAL test in the <i>"Analyze Configuration"</i> page. Affected users need to migrate their plugins to the new APIs described in the Werk linked above. The most important step, the migration of the `check_levels` function is shown in [this commit](https://github.com/Checkmk/checkmk/commit/d9b91e37443923720ed33c3e2…. All other (minor) differences between the API versions are listed in the APIs documentation found in your site (Help -> Check plugin API reference). A comprehensive guide on how to write plugins is found [in our documentation](https://docs.checkmk.com/latest/en/devel_check_plugins.html).