Cannot select metric items on the custom monitoring page

Created by: LinuxSuRen

General remarks

This form is to report bugs. For general usage questions refer to our Slack channel KubeSphere-users

Describe the bug When I try to add metrics of argocd, it's not able to get all metrics due the UI issues.

Versions used(KubeSphere/Kubernetes) KubeSphere: kubespheredev/ks-console:nightly-20210420

Environment This is not an environmental issue.

To Reproduce Steps to reproduce the behavior:

1. Go to the Custom Monitoring page
2. Find a metrics category that has a lot

Expected behavior Users can get all metrics of a component.