fix(module: tree): fix nzHideUnMatched bug

[simplejason]

close #3970

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: #3970

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #4286 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4286      +/-   ##
==========================================
+ Coverage   92.18%   92.19%   +<.01%     
==========================================
  Files         520      520              
  Lines       11011    11012       +1     
  Branches     1995     1995              
==========================================
+ Hits        10150    10152       +2     
  Misses        430      430              
+ Partials      431      430       -1

Impacted Files	Coverage Δ
components/core/tree/nz-tree-base.service.ts	94.02% <100%> (+0.02%)	⬆️
components/dropdown/nz-dropdown.component.ts	95.83% <0%> (+2.08%)	⬆️

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[vthinkxie]

LGTM