perf(module:dropdown): do not run change detection if the dropdown has been clicked inside

[arturovt]

PR Checklist

• 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

[x] Refactoring (no functional changes, no api changes)

Does this PR introduce a breaking change?

[ ] Yes
[x] No

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #7135 (81a1659) into master (ab78821) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7135      +/-   ##
==========================================
+ Coverage   89.75%   89.77%   +0.01%     
==========================================
  Files         488      488              
  Lines       15937    15948      +11     
  Branches     2579     2579              
==========================================
+ Hits        14304    14317      +13     
+ Misses       1001      998       -3     
- Partials      632      633       +1     

Impacted Files	Coverage Δ
components/dropdown/context-menu.service.ts	96.42% <100.00%> (+0.42%)	⬆️
components/input/input.directive.ts	93.93% <0.00%> (-3.04%)	⬇️
components/cascader/cascader.service.ts	97.07% <0.00%> (-0.49%)	⬇️
components/tree/tree-node.component.ts	90.37% <0.00%> (-0.39%)	⬇️
components/layout/sider.component.ts	94.82% <0.00%> (ø)
components/cascader/cascader-li.component.ts	100.00% <0.00%> (ø)
components/transfer/transfer-list.component.ts	96.22% <0.00%> (ø)
components/cascader/cascader.component.ts	94.79% <0.00%> (+0.03%)	⬆️
components/tree/tree.component.ts	92.65% <0.00%> (+0.04%)	⬆️
components/skeleton/skeleton-element.component.ts	95.00% <0.00%> (+0.26%)	⬆️
... and 2 more

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[simplejason]

LGTM