role:monitoring_plugins: Apply versionlock to mp version only, not to package iteration

Current: 
```
$ dnf versionlock 
Last metadata expiration check: 0:00:23 ago on Sat 20 May 2023 02:47:23 PM CEST.
linuxfabrik-monitoring-plugins-0:2023051201-4.*
```
Should be on `2023051201` to be able to roll out newer installation packages for the same version.