fix(module:carousel): fix index value passed to afterchange callback

[Sreekanth2108]

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?

Index value emitted by afterChange output property when we go from either last item to first item or first item to last item is wrong.
ex:
arr = [1,2,3,4].

• when we go from 4th element to 1st element in a circular swipe manner, the index value emitted is 4 instead of 0
• when we go from 1st element to 4th element in a reverse circular swipe manner, the index value emitted is -1 instead of 3
  Below is the demo of the issue where active index value show the value emitted by afterChange output property
  https://angular-aacqoq.stackblitz.io
  Below is the editor to play with for the same issue
  https://stackblitz.com/edit/angular-aacqoq

What is the new behavior?

ex:
arr = [1,2,3,4].

• when we go from 4th element to 1st element in a circular swipe manner, the index value emitted is 0 instead of 4
• when we go from 1st element to 4th element in a reverse circular swipe manner, the index value emitted is 3 instead of -1

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

No existing test cases to modify for this change

[codecov]

Codecov Report

Merging #4753 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4753   +/-   ##
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  Coverage   93.27%   93.27%           
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  Files         502      502           
  Lines       12679    12679           
  Branches     2011     2011           
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  Hits        11826    11826           
  Misses        443      443           
  Partials      410      410           

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[Laffery]

already fixed