fix(module: tree): fix nzMultiple and rollback code

[simplejason]

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: #3076

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 8514b5f

https://deploy-preview-3060--ng-zorro-master.netlify.com

[codecov]

Codecov Report

Merging #3060 into master will increase coverage by 0.03%.
The diff coverage is 96.35%.

@@            Coverage Diff             @@
##           master    #3060      +/-   ##
==========================================
+ Coverage    97.3%   97.34%   +0.03%     
==========================================
  Files         550      552       +2     
  Lines       11539    11587      +48     
  Branches      826      827       +1     
==========================================
+ Hits        11228    11279      +51     
+ Misses        201      195       -6     
- Partials      110      113       +3

Impacted Files	Coverage Δ
components/tree/nz-tree-node.component.ts	97.14% <ø> (+0.44%)	⬆️
components/tree/nz-tree.module.ts	100% <ø> (ø)	⬆️
components/tree/public-api.ts	100% <100%> (ø)	⬆️
components/tree/nz-tree-node.ts	91.72% <91.93%> (+2.74%)	⬆️
components/tree/nz-tree-base.service.ts	96.77% <98.21%> (-0.11%)	⬇️
components/tree/nz-tree.component.ts	98.77% <98.63%> (-0.66%)	⬇️
components/cascader/types.ts
components/cascader/nz-cascader-definitions.ts	100% <0%> (ø)
components/cascader/nz-cascader.service.ts	98.87% <0%> (ø)
components/cascader/nz-cascader-utils.ts	100% <0%> (ø)
... and 4 more

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