fix(module:radio): fix radio ContentChildren error

[vthinkxie]

close #2206 close #2611

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:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

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[codecov]

Codecov Report

Merging #2660 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2660      +/-   ##
==========================================
- Coverage   95.63%   95.62%   -0.01%     
==========================================
  Files         495      495              
  Lines       12079    12079              
  Branches     1687     1687              
==========================================
- Hits        11552    11551       -1     
  Misses        169      169              
- Partials      358      359       +1

Impacted Files	Coverage Δ
components/radio/nz-radio-group.component.ts	93.33% <100%> (ø)	⬆️
components/time-picker/time-holder.ts	95.91% <0%> (-1.03%)	⬇️

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