fix: reduce PMU multiplexing influence

[bowen-intel]

Ⅰ. Describe what this PR does

By amplifying the results obtained through 'perf_event_open', reduce the error caused by PMU (Performance Monitoring Unit) time multiplexing when calculating CPI.

Ⅱ. Does this pull request fix one issue?

fixes #1470

Ⅲ. Describe how to verify it

By Grafana?

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: 33.33% and project coverage change: -0.01% ⚠️

Comparison is base (d3ac7f4) 64.12% compared to head (7a6b122) 64.11%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1489      +/-   ##
==========================================
- Coverage   64.12%   64.11%   -0.01%     
==========================================
  Files         342      342              
  Lines       35204    35210       +6     
==========================================
+ Hits        22573    22575       +2     
- Misses      10966    10970       +4     
  Partials     1665     1665              

Flag	Coverage Δ
unittests	64.11% <33.33%> (-0.01%)	⬇️

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

Files Changed	Coverage Δ
pkg/koordlet/util/perf/perf_linux.go	46.73% <9.09%> (-3.27%)	⬇️
...lectors/performance/performance_collector_linux.go	56.00% <100.00%> (ø)
pkg/koordlet/util/stat.go	75.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[jasonliu747]

/cc @songtao98

[hormes]

/lgtm

[songtao98]

I found a different computing formula for scalingRatio on kernel Tutorial but this PR's implementation is better for understanding.

[songtao98]

/lgtm
/cc @hormes @zwzhang0107

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes, songtao98

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