fix(module: tree): fix nzCheckStrictly and nzShowIcon and remove

[simplejason]

fix(module: tree): fix nzCheckStrictly nzShowIcon and remove

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
[x] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: #1399 #2370 #2655 #2724

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 a8c6871

https://deploy-preview-2805--ng-zorro-master.netlify.com

[codecov]

Codecov Report

Merging #2805 into master will increase coverage by <.01%.
The diff coverage is 93.33%.

@@            Coverage Diff             @@
##           master    #2805      +/-   ##
==========================================
+ Coverage   95.53%   95.53%   +<.01%     
==========================================
  Files         517      517              
  Lines       12264    12277      +13     
  Branches     1692     1694       +2     
==========================================
+ Hits        11716    11729      +13     
  Misses        189      189              
  Partials      359      359

Impacted Files	Coverage Δ
components/tree/nz-tree.component.ts	95.23% <100%> (+0.11%)	⬆️
components/tree/nz-tree-node.component.ts	95.32% <100%> (+0.02%)	⬆️
components/tree/nz-tree-node.ts	91.78% <90%> (-0.41%)	⬇️
components/time-picker/time-holder.ts	96.93% <0%> (+1.02%)	⬆️

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[wzhudev]

Could use the new API, like just frown. Because old API is not suggested.