Prevent dry_run dispatch from overriding live dispatch

[Marenz]

Based on the discussion, it seems that a dry_run dispatch can potentially override a live dispatch, which could lead to inconsistencies. The following points were raised:

An actor running a dispatch should expect the dry_run state to change during the run, which can cause inconsistencies.
It was suggested to prevent this behavior to maintain consistency with the update behavior.

One approach could be to split the groups into dry and wet run dispatches, allowing them to run in parallel without interference.

The main use case for dry_run is for testing purposes, where it should not interrupt the main actor.
Supporting parallel running of dry_run and live dispatches would allow users to test new values without affecting the live dispatch.