fix: Add monitoring items to the custom monitoring panel, and the monitoring indicators display errors

Created by: weili520

Signed-off-by: TheYoungManLi cjl@kubesphere.io

What type of PR is this?

/kind bug

What this PR does / why we need it:

The problem caused by the options's top hight incorrect, It will appears when the options length less than 8.

Which issue(s) this PR fixes:

Fixes ##3358

Special notes for reviewers:

Does this PR introduced a user-facing change?

NONE

Additional documentation, usage docs, etc.: