fix(module:tabs): router link content projection error

[hsuanxyz]

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: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #5663 into master will decrease coverage by 0.22%.
The diff coverage is 46.15%.

@@            Coverage Diff             @@
##           master    #5663      +/-   ##
==========================================
- Coverage   90.31%   90.08%   -0.23%     
==========================================
  Files         455      455              
  Lines       13788    13798      +10     
  Branches     2258     2182      -76     
==========================================
- Hits        12452    12430      -22     
- Misses        819      844      +25     
- Partials      517      524       +7     

Impacted Files	Coverage Δ
components/tabs/tab.component.ts	92.59% <0.00%> (ø)
components/tabs/tabs.module.ts	100.00% <ø> (ø)
components/tabs/tab-link.directive.ts	37.50% <28.57%> (-62.50%)	⬇️
components/tabs/tabset.component.ts	86.54% <80.00%> (-9.86%)	⬇️
components/tabs/tabs-ink-bar.directive.ts	83.87% <0.00%> (-3.23%)	⬇️
components/tabs/tab-nav-bar.component.ts	82.33% <0.00%> (-2.48%)	⬇️
components/core/util/text-measure.ts	89.56% <0.00%> (-1.74%)	⬇️

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