test(module:auto-complete): added missing tests

[ParsaArvanehPA]

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: missing unit tests for the Auto-complete Component

What is the current behavior?

What is the new behavior?

	Before	After
Statements	97.31%	98.65%
Branches	98.31%	100%
Functions	95.78%	96.84%
Lines	97.9%	99.3%

Does this PR introduce a breaking change?

• Yes
• [✔] No

Other information

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.17%. Comparing base (dd42ad9) to head (ed0f139).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8780      +/-   ##
==========================================
+ Coverage   93.15%   93.17%   +0.02%     
==========================================
  Files         538      538              
  Lines       18457    18457              
  Branches     2816     2816              
==========================================
+ Hits        17193    17198       +5     
+ Misses       1226     1221       -5     
  Partials       38       38              

Flag	Coverage Δ
	93.17% <ø> (?)

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[Laffery]

LGTM