Suppressing Problems for GC regarding a specific process group is surprisingly difficult to do. Like Babar said, you can only configure it on a global or host level. But that doesn't satisfy the use case described here, i.e. configuring it for a specific process (group) only.
What you can do is to first tag that process, and then create a maintenance window which disables Problem generation for that tag scope. Of course the side effect is that Dynatrace will always show that process as being under maintenance. Also, you would additionally suppress other issues related to the process, like TCP connectivity Problems.
Well, if someone has a better solution, I'm interested in hearing it 🙂 The above method anyway works if you can live with the side effects.