You may have figured this out already but since the docs are a bit lite on configuring Camunda generic-properties I thought I would post this info. Below is an example of configuring history.
There are a few options for configuring History Cleanup. All the options rely on the process engine configuration of some sort.
See Option 3 to use generic-properties which is what I think will work for your case. Included the other options just in case.
1. You can utilize process.xml or camunda.cfg.xml as described here.
In the case of spring-boot you can utilize Component Scanning and @Value annotations to quickly create your own properties and hook this into a yaml config via a process-engine-plugin.
To use generic-properties just find the property in the configuration-properties doc above than add a hyphen “-” between words and remove camel case like historyCleanupStrategy becomes history-cleanup-strategy.