fix(module:collapse): fix collapse

[vthinkxie]

close #2567

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?

[ ] 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: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

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[codecov]

Codecov Report

Merging #2597 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2597      +/-   ##
==========================================
+ Coverage   95.63%   95.65%   +0.02%     
==========================================
  Files         495      495              
  Lines       12062    12056       -6     
  Branches     1678     1677       -1     
==========================================
- Hits        11535    11532       -3     
+ Misses        168      167       -1     
+ Partials      359      357       -2

Impacted Files	Coverage Δ
components/collapse/nz-collapse.component.ts	100% <100%> (+6.89%)	⬆️
components/collapse/nz-collapse-panel.component.ts	100% <100%> (ø)	⬆️
components/time-picker/time-holder.ts	96.93% <0%> (+1.02%)	⬆️

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