perf(module: picker): perf delete default data in component.

[Guoyuanqiang]

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-mobile/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
[x] 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

[codecov]

Codecov Report

Merging #272 into master will decrease coverage by 0.04%.
The diff coverage is 70.49%.

@@            Coverage Diff             @@
##           master     #272      +/-   ##
==========================================
- Coverage    86.5%   86.46%   -0.05%     
==========================================
  Files         229      228       -1     
  Lines        7374     7401      +27     
  Branches     1053     1063      +10     
==========================================
+ Hits         6379     6399      +20     
- Misses        584      589       +5     
- Partials      411      413       +2

Impacted Files	Coverage Δ
components/picker/picker.directive.ts	88.88% <64.7%> (-4.54%)	⬇️
components/picker/picker.component.ts	71.13% <72.22%> (+1.08%)	⬆️
components/picker-view/picker-view.component.ts	94.59% <75%> (-5.41%)	⬇️

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