Feature Request

Is your feature request related to a problem? Please describe:

Now we can not know what's the maximum available CPU/Memory on Grafana panel, especially on k8s deployed env.

Describe the feature you'd like:

Show the maximum available CPU/Memory on TiFlash Grafana panel.
I've created a basic branch for getting the maximum available CPU/Memory quota: https://github.com/JaySon-Huang/tics/commits/fix_cpu_count

The show style could be like this:

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

Useful for checking whether TiFlash resource is running out, especially on k8s env