fix(module:tree-select): width is 0 when trigger element is invisible

[hsuanxyz]

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: #1772

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #1775 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1775      +/-   ##
==========================================
- Coverage   96.05%   96.03%   -0.02%     
==========================================
  Files         466      466              
  Lines       11153    11157       +4     
  Branches     1458     1459       +1     
==========================================
+ Hits        10713    10715       +2     
  Misses        127      127              
- Partials      313      315       +2

Impacted Files	Coverage Δ
components/tree-select/nz-tree-select.component.ts	98.6% <100%> (-0.45%)	⬇️
components/time-picker/time-holder.ts	95.91% <0%> (-1.03%)	⬇️

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