fix(module:date-picker): click outside not change value

[wenqi73]

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: #6595

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #6596 (a62ae0e) into master (825925c) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head a62ae0e differs from pull request most recent head 0bafcf1. Consider uploading reports for the commit 0bafcf1 to get more accurate results

@@           Coverage Diff           @@
##           master    #6596   +/-   ##
=======================================
  Coverage   89.92%   89.93%           
=======================================
  Files         481      481           
  Lines       15380    15379    -1     
  Branches     2344     2344           
=======================================
  Hits        13831    13831           
- Misses        929      931    +2     
+ Partials      620      617    -3     

Impacted Files	Coverage Δ
components/date-picker/date-picker.component.ts	93.37% <100.00%> (-0.13%)	⬇️
components/date-picker/picker.component.ts	91.76% <100.00%> (+1.82%)	⬆️
components/image/image.directive.ts	89.39% <100.00%> (+0.16%)	⬆️
components/upload/upload-list.component.ts	95.86% <100.00%> (ø)
...mponents/date-picker/date-range-popup.component.ts	89.78% <0.00%> (-1.62%)	⬇️
...ponents/time-picker/time-picker-panel.component.ts	89.11% <0.00%> (+0.40%)	⬆️

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