apis: add system usage in NodeMetric

[zwzhang0107]

Ⅰ. Describe what this PR does

see #991

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.02 ⚠️

Comparison is base (36c99b7) 64.91% compared to head (53281b6) 64.90%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1262      +/-   ##
==========================================
- Coverage   64.91%   64.90%   -0.02%     
==========================================
  Files         312      312              
  Lines       32660    32660              
==========================================
- Hits        21202    21198       -4     
- Misses       9905     9910       +5     
+ Partials     1553     1552       -1     

Flag	Coverage Δ
unittests	64.90% <ø> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

see 3 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[saintube]

/lgtm

[eahydra]

/lgtm
/approve

[FillZpp]

/lgtm
/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: eahydra, FillZpp

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• apis/OWNERS [FillZpp]
• config/OWNERS [eahydra]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment