Revise memory headroom calculation to reduce OOM

[jinxin32]

What type of PR is this?

Enhancements

What this PR does / why we need it:

Which issue(s) this PR fixes:

Special notes for your reviewer:

Related PR: kubewharf/katalyst-api#182

[codecov]

Codecov Report

❌ Patch coverage is 93.05556% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.56%. Comparing base (55ffd45) to head (718d604).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...esource/memory/headroompolicy/policy_numa_aware.go	93.87%	2 Missing and 1 partial ⚠️
...qos/reclaimedresource/memoryheadroom/util_based.go	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1128      +/-   ##
==========================================
- Coverage   61.57%   61.56%   -0.02%     
==========================================
  Files         783      783              
  Lines       73224    73285      +61     
==========================================
+ Hits        45091    45120      +29     
- Misses      23129    23154      +25     
- Partials     5004     5011       +7     

Flag	Coverage Δ
unittest	61.56% <93.05%> (-0.02%)	⬇️

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