CI: Simplify CodeQL

[Zeroto521]

• closes #xxxx
• whatsnew entry

Two mainly changes

• only trigger via schedule event
• remove extra jobs and comments

[codecov]

Codecov Report

Merging #700 (86cbf36) into main (d5c8657) will decrease coverage by 0.14%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #700      +/-   ##
==========================================
- Coverage   99.55%   99.40%   -0.15%     
==========================================
  Files         114      114              
  Lines        1334     1334              
  Branches      121      121              
==========================================
- Hits         1328     1326       -2     
- Misses          1        2       +1     
- Partials        5        6       +1     

Impacted Files	Coverage Δ
dtoolkit/transformer/sklearn/OneHotEncoder.py	92.30% <0.00%> (-7.70%)	⬇️

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