fix(module:carousel): fix nzAfterChange callback value not correctly

[chenc041]

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: #7323

What is the new behavior?

nzAfterChange callback return correctly
Closed: #7323

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 #7326 (c50a5d5) into master (2d77bc2) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7326      +/-   ##
==========================================
+ Coverage   91.59%   91.63%   +0.04%     
==========================================
  Files         487      487              
  Lines       16006    16006              
  Branches     2604     2604              
==========================================
+ Hits        14660    14667       +7     
+ Misses       1033     1025       -8     
- Partials      313      314       +1     

Impacted Files	Coverage Δ
components/carousel/carousel.component.ts	92.68% <100.00%> (ø)
components/table/src/table-style.service.ts	94.82% <0.00%> (-1.73%)	⬇️
components/tabs/tab-nav-bar.component.ts	87.94% <0.00%> (+0.70%)	⬆️
components/table/src/table/tr-measure.component.ts	91.30% <0.00%> (+4.34%)	⬆️
...ts/table/src/table/table-inner-scroll.component.ts	83.82% <0.00%> (+4.41%)	⬆️
components/table/src/table/tbody.component.ts	100.00% <0.00%> (+11.11%)	⬆️

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[wzhudev]

LGTM. Thanks!