We prefer to use the built-in PipelineRun GC instead of Jenkins itself. Please feel free to configure the CronJob according to your requirement.
Normally, you could find it from namespace kubesphere-devops-system. You could specifiy the following options:
maxAgeis the maximum time to live for PipelineRunsmaxCountis the max number of the PipelineRuns
See also the Helm chart values setting.