fix(module:dropdown): fix dropdown disabled button

[vthinkxie]

close #5258

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

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #5429 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5429   +/-   ##
=======================================
  Coverage   91.20%   91.21%           
=======================================
  Files         551      551           
  Lines       13980    13995   +15     
  Branches     2118     2121    +3     
=======================================
+ Hits        12751    12765   +14     
  Misses        733      733           
- Partials      496      497    +1     

Impacted Files	Coverage Δ
components/dropdown/dropdown.directive.ts	88.77% <100.00%> (+0.60%)	⬆️
components/input/input.directive.ts	96.15% <0.00%> (-3.85%)	⬇️

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