fix(pro:transfer): tree transfer count error under child strategy

[sallerli1]

PR Checklist

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• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

树穿梭框在级联策略 'child' 下，由于选中的数量只计算了叶子节点，全选之后待选数量仍然不为0，计算不正确

What is the new behavior?

修复以上问题

Other information

[idux-bot]

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[codecov]

Codecov Report

Merging #1443 (a1898e2) into main (7829ca1) will not change coverage.
The diff coverage is 100.00%.

❗ Current head a1898e2 differs from pull request most recent head 40fedd6. Consider uploading reports for the commit 40fedd6 to get more accurate results

@@           Coverage Diff           @@
##             main    #1443   +/-   ##
=======================================
  Coverage   92.81%   92.81%           
=======================================
  Files         327      327           
  Lines       30349    30349           
  Branches     2546     2547    +1     
=======================================
  Hits        28168    28168           
  Misses       2181     2181           

Impacted Files	Coverage Δ
packages/cdk/utils/src/tree.ts	98.40% <100.00%> (ø)

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