chore: improve calculate mysql buffer pool size in 0.9

[kizuna-lek]

No description provided.

[kizuna-lek]

/approve

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 64.90%. Comparing base (a12dc4a) to head (a4bd848).
Report is 2 commits behind head on release-0.9.

Files with missing lines	Patch %	Lines
pkg/controller/configuration/builtin_functions.go	75.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-0.9    #8343      +/-   ##
===============================================
+ Coverage        64.83%   64.90%   +0.07%     
===============================================
  Files              358      358              
  Lines            45310    45311       +1     
===============================================
+ Hits             29376    29411      +35     
+ Misses           13303    13274      -29     
+ Partials          2631     2626       -5     

Flag	Coverage Δ
unittests	64.90% <75.00%> (+0.07%)	⬆️

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