fix(module:tabs): fix clickable area of tab-link

[hsuanxyz]

close #5696

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

[codecov]

Codecov Report

Merging #5708 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5708   +/-   ##
=======================================
  Coverage   90.09%   90.09%           
=======================================
  Files         455      455           
  Lines       13798    13797    -1     
  Branches     2183     2183           
=======================================
  Hits        12431    12431           
+ Misses        843      842    -1     
  Partials      524      524           

Impacted Files	Coverage Δ
components/tabs/tabset.component.ts	87.05% <ø> (+0.50%)	⬆️

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