fix(module:auto-complete): not emit changes when retype same value while open

[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

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[codecov]

Codecov Report

Merging #4215 into master will decrease coverage by <.01%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master    #4215      +/-   ##
==========================================
- Coverage   92.31%   92.31%   -0.01%     
==========================================
  Files         519      519              
  Lines       10963    10968       +5     
  Branches     1984     1986       +2     
==========================================
+ Hits        10121    10125       +4     
- Misses        419      420       +1     
  Partials      423      423

Impacted Files	Coverage Δ
...auto-complete/nz-autocomplete-trigger.directive.ts	96.03% <88.88%> (+0.16%)	⬆️
components/typography/nz-typography.component.ts	97.93% <0%> (-1.04%)	⬇️

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[vthinkxie]

LGTM