fix(module:auto-complete): can't select option when touch

[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: #2053

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #2054 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #2054   +/-   ##
=======================================
  Coverage   96.01%   96.01%           
=======================================
  Files         470      470           
  Lines       11424    11424           
  Branches     1515     1515           
=======================================
  Hits        10969    10969           
  Misses        131      131           
  Partials      324      324

Impacted Files	Coverage Δ
...auto-complete/nz-autocomplete-trigger.directive.ts	96.75% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 69e1f5f...62c71fb. Read the comment docs.