fix(module:tooltip): fix position change not set back

[wzhudev]

close #3467

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: #3467

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[netlify]

Deploy preview for ng-zorro-master ready!

Built with commit 6c50450

https://deploy-preview-3857--ng-zorro-master.netlify.com

[netlify]

Deploy preview for ng-zorro-master ready!

Built with commit 9f594da

https://deploy-preview-3857--ng-zorro-master.netlify.com

[codecov]

Codecov Report

Merging #3857 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3857      +/-   ##
==========================================
- Coverage   95.36%   95.36%   -0.01%     
==========================================
  Files         723      723              
  Lines       14722    14722              
  Branches     1937     1937              
==========================================
- Hits        14040    14039       -1     
  Misses        249      249              
- Partials      433      434       +1

Impacted Files	Coverage Δ
components/tooltip/nz-tooltip.component.ts	88.88% <100%> (-1.59%)	⬇️

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[vthinkxie]

LGTM